HomeMy WebLinkAboutSWP272231 1
STORM DRAINAGE REPORT
' for
' SOUND MAZDA DEALERSHIP
SW CORNER OF RAINIER& GRADY
RENTON, WA
' Prepared For:
SOUND MAZDA
Renton, WA 98055
4� oV WA-s �-11
¢� I Cn
z;
� z
a
'
0 9157 �W
'an ISTE�2 ' Gti�
s`S/ONAL E� q ��IG�
' EXPIRES 9/21/ , I t 1
' Prepared By:
WARNER ENGINEERING
5122 Olympic Drive NW, Suite B204
' Gig Harbor, WA 98335
(206) 858-8577
' September 15, 1995 I
Job Number: 023001 f
1
i_
STORM DRAINAGE REPORT
for
SOUND MAZDA DEALERSHIP
SW CORNER OF RAINIER& GRADY
RENTON, WA
Prepared For:
SOUND MAZDA
Renton, WA 98055
E _ W
C5 FT �'a
z
w
� 6 157
•SSA_,`�
EXPIRES 9/21/
Prepared By:
WARNER ENGINEERING
5122 Olympic Drive NW, Suite B204
Gig Harbor, WA 98335
(206) 858-8577
September 15, 1995
Job Number: 023001
1 ! ,
' TABLE OF CONTENTS
' I. Project Overview
tII. Existing Conditions Summary
III. Developed Conditions Summary
IV. Discussion of Core Requirements
' V. Discussion of Special Requirements
VI. Conveyance System Analysis and Design
' VII. Water Quality Analysis and Design
' VIII. Appendices
Appendix A- Vicinity Map
' Appendix B - SCS Soil Map
Appendix C -Predeveloped Basin Map
Appendix D - Postdeveloped Basin Map
' Appendix E - Isopluvial Maps: 2-, 10-, 100- Year
Appendix F - Runoff Coefficients
Appendix G- Waterworks program Calculations
' Pre-developed Data
Post-developed Data
Appendix H - Technical Information Report Worksheet
' Appendix I - Geotechnical Engineering Study
IX. References
1
1
1
2
1
I. PROJECT OVERVIEW
' This project is a new two story Mazda dealership. The site is bounded on the north by
SW Grady Way, on the east by Rainier Ave., and on the south by SW 12th Street. The
' project encompasses development of the entire 1 acre site. The work shall include the
construction of a 15,196 SF building, driveway access from Grady Way and SW 12th
Street, parking and vehicle display area. The project will require the vacation of an alley
' and a street use permit to utilize the right-of-way of SW 12th Street for parking and
vehicle backup room.. See Appendix A for a vicinity map.
II. EXISTING CONDITIONS SUMMARY
SOILS
' Soils on the site are identified by the SCS Soil Survey for King County' as Urban Land
(U)- see Appendix B for SCS Soils information. The SCS description is as follows:
' Urban land(U) is soil that has been modified by disturbance of the natural layers
' with additions of fill material several feet thick to accommodate large industrial
and housing installations. In the Green River Valley the fill ranges from about 3
to more than 12 feet in thickness, and from gravelly sandy loam to gravelly loam
' in texture.
The erosion hazard is slight to moderate. No capability or woodland
classification.
Based upon the geotechnical data we will assume that a hydrologic soil group C soil is
' present on the site.
EXISTING DEVELOPMENT AND DRAINAGE
The site currently is comprised of grass and gravel areas which are used for truck storage.
The site generally slopes to the south, with a total vertical relief of about 6 feet. Surface
drainage on site is sheet flow to an existing catch basin located near the southwest corner
of the property. That flow enters the existing City storm system located in SW 12th
Street. See the Predeveloped Basin Map, Appendix C.
' OFF-SITE AND DOWNSTREAM DRAINAGE
There is no off-site drainage onto this site. See the Predeveloped Basin Map,
' Appendix C.
3
1
tWater leaving this site generally sheet flows to the catch basin located in the southwest
' corner of the property. The storm system flows west in a 12" PVC pipe to the
intersection of SW 12th St. and Maple Ave. SW. At this point it continues south in an
18" CMP pipe. Per the Preliminary Drainage Report for Renton Dodge Dealerships the
18" line turns into a 24" line turns and continues west along I-405 in a 24" culvert. The
culvert discharges to a ditch and then flows back into a 24" line. The flow continues west
and the pipe changes to a 30" pipe at the intersection of Lind Ave and I-405. The flow
' passes under I-405 where is discharges to a ditch which flows west. It continues flowing
west to the pumping station at Oaksdale Ave SW. The pumped water is discharged to a
system which outlets to Springbrook Creek. Springbrook Creek flows northwest to the
' Green River.
III. DEVELOPED CONDITIONS SUMMARY
' ON-SITE DEVELOPMENT AND DRAINAGE
' The new dealership building will be approximately 15,000 square feet and be located on
the portion of the site surrounded by the parking and display areas. Storm drainage for
' the site will be as follows:
The site will be graded to sheet flow to a concrete gutter that will connect to a new storm
' pipe. The pipe discharges to the water quality oil/water separator and is released to the
existing 12" line along SW 12th Street. Downspouts will be piped to the storm system
where possible. Because the existing storm system is too shallow, some downspouts will
' be directed through sidewalk drains, overland to the concrete gutter. The increase in
run-off from the Pre-developed condition to the Developed condition is less that 0.5 cfs,
therefore no detention is proposed for this site. A small area is designated for vehicle
' washing. The waste water from this area will be collected in an area drain and routed
through an oil/water separator and be discharged to the sanitary sewer system.
' Water quality for those areas subject to vehicular traffic will be by use of a baffle type
oil/water separator. Due to the small area on the site and the shallow existing storm
system, a biofiltration Swale is not possible. A baffle-type oil/water separator is proposed
' using a manhole rather than a large vault since the volume of the water quality storm is
only 0.4 ac-ft or 1740 cf with a rate of 0.11 cfs. See the Postdeveloped Basin Map,
Appendix D.
' OFF-SITE IMPROVEMENTS AND DRAINAGE
' No off-site improvements are proposed.
4
IV. DISCUSSION OF CORE REQUIREMENTS
' Core Requirement #1- Discharge at the Natural Location
' As discussed in EXISTING CONDITIONS SUMMARY above, the site drainage
currently drains to the catch basin located at the southwest corner of the property. The
proposed storm system will connect to this same storm system.
' Core Requirement #2- Off-Site Analysis
No offsite drainage enters the site. See Appendix C- Predeveloped Basin Map. A Level
One Downstream Analysis is described in the Existing Conditions Summary. There are no
known drainage problems in this system.
' Core Requirement #3- Runoff Control
' This site is exempt from On-site Peak Rate Runoff Control because the increase in the
peak runoff is less than 0.5 cfs more than the peak runoff rate for the existing site
conditions. yr .-CoC Fa4(E G a 7 y
' Core Requirement #4- Conveyance System
' The project storm system will convey the site 100 year design storm.
Core Requirement #5-Erosion/Sedimentation Control Plan
' An Erosion and sedimentation plan has been developed for this site as outlined in the King
County Surface Water Design Manual. Filter fences, CB inlet protection, CB inlet
sediment trap and construction entrances will be installed.
Core Requirement #6-Maintenance and Operation
Maintenance and operation of all of the stormwater system on this site will be the
responsibility of the Renton Mazda Dealership.
' Core Requirement#7-Bonds and Liability
' Bonds and liability insurance will be provided by the Renton Mazda Dealership.
5
V. DISCUSSION OF SPECIAL REQUIREMENTS
Special Requirement #1- Critical Drainage Areas
The City has not indicated that this site is in a critical drainage basin.
Special Requirement #2- Compliance With Existing Master Drainage Plan
There is no existing known Master Drainage Plan that includes this site.
' Special Requirement 43- Conditions Requiring a Master Drainage Plan
This project site does not trigger any of the thresholds that require a Master Drainage
' Plan.
Special Requirement #4- Adopted Basin or CommunityPlans
lans
The site is not in any known adopted basin or community plans.
' Special Requirement #5- Special Water Quality Controls
' There is less than 1 acre of new impervious area subject to vehicular traffic. This project
provides a water quality oil/water separator system that is designed per Department of
Ecology Stormwater Management Manual for the Puget Sound.
' Special Requirement #6- Coalescing Plate Oil/Water Separators
' This site is will have less than 5000 square feet that is subject to petroleum storage, high
vehicle usage, or heavy equipment use and is therefore exempt from a coalescing plate
oil/water separator.
' Special Requirement #7- Closed Depression
There are no closed depressions on the project site.
' Special Requirement 98- Use of Lakes. Wetlands or Closed Depressions for Peak Runoff
Control
' The project will not use a lake, wetland or closed depression for peak runoff control.
Special Requirement #9- Delineation of 100 Year Floodplain
' The project neither contains nor abuts any 100 year floodplains.
6
tSpecial Requirement #10- Flood Protection Facilities for Type 1 and 2 Streams
This project does not abut a Type 1 or 2 stream and we do not propose to construct a
new, or modify an existing, flood protection facility. This site is therefore exempt from
' this requirement.
Special Requirement 411- Geotechnical Analysis and Report
' A geotechnical analysis and report is not required for this project, but is offered as
Appendix H.
Special Requirement#12- Soils Analysis and Report
Soils report is included as Appendix H.
Special Requirement #13 - Aquifer Recharge and Protection Areas
' This site is not in an aquifer recharge or protection area.
' VI. CONVEYANCE SYSTEM ANALYSIS AND DESIGN
See Appendix G. Summarized below are the design data
' Constants
' P2 = 2 in. Soil Type C
P,o = 2.9 in. CN= 86.0 grass
P100= 3.9 in. CN= 89.0 gravel
' CN= 98.0 impervious
Existing conditions
' Q2 = 0.16 cfs APB,,,= 1.04 ac T, = 21.80 min.
Q,o= 0.32 cfs Ai'P = 0.04 ac
' Q100= 0.51 cfs
Developed conditions
Q2 = 0.42 cfs APB,= 0.08 ac T,= 44.91 min.
' Q,o= 0.62 cfs Ai'P = 1.00 ac
Qioo
= 0.85 cfs
Water Quality treatment rate= Q6mu= 0.11 cfs
7
tCapacity of SW 12th Street pipe: 302 LF - 12" DI @ 0.27%
' (Using Flowmaster6)
Our assumption is that the area to the south of SW 12th Street draining into this
conveyance system is approximately equal to the area north of SW 12th Street (the Sound
' Mazda site).
Q10 = 2(0.62 cfs) = 1.24 cfs vl0= 2.69 fps
' Q10= 2(0.85 cfs) = 1.70 cfs vlo =2.86 fps
See Appendix G for Flowmaster Printouts.
' VII. WATER QUALITY ANALYSIS AND DESIGN
A. The oil/water separator orifice is sized for the 100-year storm event so that only
extreme events will cause an overflow situation
' Q = CA(2gh)05 h=4 ft. g=32.2 C =0.62
A= 0.85/(0.62[2(32.2)(4)]0') =0.085 sf.
A= (3.14/4)D2 D = 4A/3.14 = 0.33 ft = 3.96 in.
' 8
1
1
V. APPENDICES
' Appendix A- Vicinity Map
Appendix B - SCS Soil Map
Appendix C - Predeveloped Basin Map
' Appendix D -Postdeveloped Basin Map
Appendix E - Isopluvial Maps: 2-, 10-, 100- Year
Appendix F -Runoff Coefficients
' Appendix G- Waterworks program Calculations
Pre-developed Data
Post-developed Data
' Appendix H - Technical Information Report Worksheet
Appendix I- Geotechnical Engineering Study
' 9
— N`b,. �• �`:>-`' . aA.R R' `I � ".APPENDIX A
' BIG C STDRE '—IN
t Lot I -� ui
15 Acres Q
>
I
ew 2fAC fT[` 7J '.
__ — _ ___ —. —_ ___.__ ___ —J._._C[. rt
1 W L 33 u
'z rcr •• i RENTONI LDNCR
AL. IE
4.35A
5y TL 1 aA ssc "
er �• �`�
1
1 y ZISAc.
aA ' m Y.C�j3
1 N" B
TL t^ >:
5 f}
W C
90
w� 3r n A i f tiF
15
ISO
—————— -----
VACArfD
I' i . 2019 y1171 IS 117 + (Z) J
3i .. 'j
W.
II —II
621I76 tS}24.12 12221 42143.µI4S "�~rr l 1, .' ; 1
137
7G:35,1 • y j01 : ico: _L �� �J
,a�jD131I3 RI .H J✓' — : vyFarLo -- -' q
ST 34 41511 1312 I .a t r
� ll;toi9 iI6:11 I .. i .. ' .4niSp•SI � - ':I :::i �•J ' 'a0 .. ,ry�� 1a, ` T -
15� 3e '�45�46 Z
1I26 I42
,
r o •
36
1� ,12ai 4,
OS T '' fSCA�i zo 9 V I r
6
1312111 ID '• '•'• •''
is S o u I :.h R e Int o `: NOR.-I H
? ::OVE CROP- :c:•:•fii•:::•:r:�7 :<{•ir'.:.
. . :•..i=F'!�]'y["••CROSS,. ..5 Nb.::•r r.:'r:..•::}::'::.':
li yi ii i '� No 7 r - I Aft 11C
L• ./ . :1 t i i -• �`. ,., . fie• .
'" •i ,. ><. � � APPENDIX B,
BI& ..•fiver �.\ .�►. .. AR 0 :•
41
71
s
' gc
5 `Athleb
• I ubsta'� BM' x a `Field I 7 1'LVU
1 _ • Ur AkF I.
-�A � BeC �oG •` � � _• �� �
az Be D' � > •JAf
O a . 1
F I :M ! .� ParkFo.
s I 25
• / _ • sb
W an • e • 1 a• r
m sec /v 4
a op BeD I •OeC. '�...\' r 1 ''Rh
n p I S
s J 51 Q Rp ROAD Tu e F d
hT Ur-
• m AkF 1
lacWo
--' -' � �•�, �,: °v :•t -
' Pu ur PY 13 PROJECT L'•,'. I rt i _ 'n I : . se ,z
ryg f
� Gall + -- f BeC SITE
nurse I_ r AmC �OPo�
Wo Ur IF +M16 °. I S . InC
' a el 30s4_ ♦; Sew ee ORTHE / • �, \ °, -'° - y
{bb
'A Inc 1
Substa�
A8C
¢ at ry Ur Ur ✓ 6" - -
' rc .\�D120
:e .
i.•.a. 1 .
' f \ ;Longacrei . � Pu
. •5- t r.• ,..
Pu o./ 5ii
R f I t
<OS v Vr� •� I fl it Lam': PY 1 Wo eD ui• SBeC y
1
Track ;� --- I .•a WN _ ----- —
jv
e 1 -� ii 29• r� _ 216 ea Z
AA g r
27'30n Ur ti i i Ur
O R s rvoir
'_
z - So Tu i
• O i
i
I i Wo
Y Pu u I
25 �a03. 29
V •= 169 I AgC 1
I Ur n o
PY I 1
I T Sk , 7.
I 0 Wo Ur a e,
t A
IUr Tu I .•A _
I,. ge
I a So AgD
7 • •'
17;_ ..a
I P
.Y Wo 9M 1941 Ib.
Wo AE
1 1 1 t 3
t• 'lli F 1 Ai
^:
fr
�I Ur a; 7 . i o 1 L .nx :.. •t.
Ng
` - PyI - ,
_ Ur
0
s Ng I n 327
I BM 3 A AgC n '. .3 1 Age ,o
d r351 r L� Wo
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
' (2) CN values can be area weighted when they apply to pervious areas of similar CN's (within 20
CN points). However, high CN areas should not be combined with low CN areas (unless the
low CN areas are less than 15% of the subbasin). In this case, separate hydrographs should be
generated and summed to form one hydrograph.
FIGURE 3.5.2A HYDROLOGIC SOIL GROUP OF THE SOILS INKING COUNTY
HYDROLOGIC HYDROLOGIC
SOIL GROUP
GROUP` SOIL GROUP GROUP*
'
C Orcas Peat D Alderwood Oridia D
Arents, Aldenvood Material 0 C
Arents, Everett Material B Ovall C
Beausite C Pilchuck D
' Bellingham D Puget e
B p Puyallup B
Buckley
y p Ragnar
Renton D
Coastal Beaches Variable Variable
' Earlmont Silt Loam D Riverwash C
Edgewick C Salal D
Everett A/B `Sammamish D
Indianola A Seattle D
Kitsap C Shacar C
Klaus C Si Silt D
Mixed Alluvial Land Variable Snohomish C
Neilson A Sultan T ila D
Newberg B' Variable Nooksack C Urban D
,,. Normal Sandy Loam D Woodinville
1
' HYDROLOGIC SOIL GROUP CLASSIFICATIONS
' A. (Low runoff potential). Soils having high infiltration rates, even when thoroughly wetted, and consisting
chiefly of deep,well-to-excessively drained sands or gravels. These soils have a high rate of water
transmission.
' B. (Moderately low runoff potential). Soils having moderate infiltration rates when thoroughly wetted, and
consisting chiefly of moderately fine to moderately coarse textures. These soils have a moderate rate of
water transmission.
' C. (Moderately high runoff potential). Soils having slow infiltration rates when thoroughly wetted, and
consisting chiefly of soils with a layer that impedes downward movement of water, or soils with moderately
fine to fine textures. These soils have a slow rate of water transmission.
D. (High runoff potential). Soils having very slow infiltration rates when thoroughly wetted and consisting
chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a
hardpan or clay layer at or near the surface, and shallow soils over nearly impervious material. These sols
have a very slow rate of water transmission.
1 ' From SCS, TR-55, Second Edition, June 1986, Exhibit A•1. Revisions made from SCS, Soil Interpretation
Record, Form #5, September 1988.
1
3.5.2-2 11192
PREDEVELOPED BASIN MAP
WILµ 019 19t IWVQP YYK9
—y—
iry)pt fpp!6V.0
q fTOpf LYNII Yvf�[E •
'� CYNOCI[GURR
T^J .—JIB SItlN uE —�
yP-- 9e]rOl IlE ---F—
Surmv
lD 12-rH tT STDRIYI
fllW.II fl•fY!\�UV 161RY p1011•.IR Al.'
O®ID�pyy�N HILL COIL•IlK AT AqR Rme
wt1•Ilj M fI 1}OI IOHL HlY.t1IO
A IOmLM T W W V4 V> M 1Rbf nl MMfI R
c)rr or HEM=
WARNER ENGINEERING 9
xi9L _. L1
et=amw=n...xx off. (= ON-0z) n
g azof r� (9ue) ese-rms Gig
47 Ilmb9r, WA 98335 f �
z �
�c
S I 1 1a,8 1
r APPENDIX D
a
Ws
R $ <
p €8,
1 `�
aki
FO,
e
1 �''"•���p��s�3Av $� tl3R•dV71g 'spa '• � Z �3
' p n
i ae
f y{ y
g( ii9'1i :
w
le Z
8
F�rl
1 "
sS
I
Q
d
. 1
1
1 a 131
hill
HIM
1
• •
am..'�Waw w
S
,etN
a :�� ��;+►�'1,, � ,
WIRY
Okla
�; - SAS.
!jEsp.
. ...... �� loll
Q,.
Iry
No
wwaONE
,r
TORE
UPSI
�tSlkmv
.-�� ,�� \ Rya,, �(��:►;•�,,�•��. ���,,r�,.
wig
lot
131
pstj
1i
1 -
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN ApPENDIXF
' TABLE 3.5 2B SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS
SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982)
Runoff curve numbers for selected agricultural, suburban and urban land use for Type to
rainfall distribution, 24-hour storm duration.
CURVE NUMBERS BY
HYDROLOGIC SOIL GROUP
LAND USE DESCRIPTION A B C D
Cultivated land(1): winter condition 86 91 94 95
' Mountain open areas: low growing brush and grasslands 74 82 89 92
Meadow or pasture: 65 78 85 89
Wood or forest land: undisturbed or older second growth 42 64 76 81
Wood or forest land: young second growth or brush 55 72 81 86
Orchard: with cover crop 81 88 92 94
Open spaces, lawns, parks, golf courses, cemeteries,
landscaping.
good condition: grass cover on 75% O' or more of the area
fair_condhion: grass cover on 50%
to 75% of the area 77 85 90 92
Gravel roads and parking lots 76 85 E9 91
Dirt roads and parking lots 72 82 89
98 98 98 98
Impervious surfaces, pavement, roofs, etc.
' Open water bodies: lakes, wetlands, ponds, etc. 100 100 0 100
Single Family Residential (2)
' Dwelling Unit/Gross Acre °� Impervious (3) Separate curve number
1.0 DU/GA 15
1.5 DU/GA 20 shall be selected
2.0 DU/GA 25 for pervious and
1 2.5 DU/GA 30 impervious portion
3.0 OU/GA 34 - of the site or basin
3.5 DU/GA 38
4.0 DU/GA 42
4.5 DU/GA 46
5.0 DU/GA 48
5.5 DU/GA SO
6.0 DU/GA 52 _
6.5 DU/GA 54
7.0 DU/GA 56
Planned unit developments, % impervious
' condominiums, apartments, must be computed
commercial business and
industrial areas.
' (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering
Handbook, Section 4, Hydrology, Chapter 9, August 1972.
(2) Assumes roof and driveway runoff is directed into street/storm system.
(3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers.
3.5.2-3 11/92
2/23/95 Warner Engineering APPENDIX G
' RENTON MAZDA
PRELIMINARY STORM ANALYSIS
PREPARED BY: C. LEVEY
--------------------------------------------------
' BASIN SUMMARY
' BASIN ID: POST NAME: 2-YEAR POSTDEVELOPED STORM
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 1. 07 Acres BASEFLOWS: 0. 00 cfs
RAINFALL TYPE. . . . : TYPElA PERVIOUS AREA
PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0. 08 Acres
TIME INTERVAL. . . . : 10. 00 min CN. . . . : 86. 00
TIME OF CONC. . . . . : 4 . 73 min IMPERVIOUS AREA
' ABSTRACTION COEFF: 0.20 AREA. . : 1. 00 Acres
CN. . . . . 98. 00
TcReach - Sheet L: 200 . 00 ns: 0. 0110 p2yr: 2 . 00 s: 0. 0100
TcReach - Shallow L: 80 . 00 ks: 11. 00 s: 0. 0100
PEAK RATE: 0. 42 cfs VOL: 0 . 15 Ac-ft TIME: 480 min
BASIN ID: PRE NAME: 2-YEAR PREDEVELOPED STORM
SBUH METHODOLOGY
' TOTAL AREA. . . . . . . : 1. 07 Acres BASEFLOWS: 0 . 00 cfs
RAINFALL TYPE. . . . : TYPElA PERVIOUS AREA
PRECIPITATION. . . . : 2 . 00 inches AREA. . : 1. 03 Acres
' TIME INTERVAL. . . . : 10. 00 min CN. . . . : 86. 83
TIME OF CONC. . . . . : 21. 80 min IMPERVIOUS AREA
ABSTRACTION COEFF: 0. 20 AREA. . : 0. 04 Acres
CN. . . . : 98. 00
TcReach - Sheet L: 200. 00 ns: 0 . 1500 p2yr: 2 . 00 s: 0. 0225
TcReach - Shallow L: 80 . 00 ks: 11. 00 s: 0. 0100
PEAK RATE: 0. 16 cfs VOL: 0 . 08 Ac-ft TIME: 480 min
1
1
' 2/23/95 Warner Engineering page 1
RENTON MAZDA
PRELIMINARY STORM ANALYSIS
PREPARED BY: C. LEVEY
BASIN SUMMARY
BASIN ID: POST NAME: 10-YEAR POSTDEVELOPED STORM
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 1.07 Acres BASEFLOWS: 0. 00 cfs
' RAINFALL TYPE. . . . : TYPEIA PERVIOUS AREA
PRECIPITATION. . . . : 2.90 inches AREA. . : 0. 08 Acres
TIME INTERVAL. . . . : 10. 00 min CN. . . . : 86. 00
' TIME OF CONC. . . . . : 4.73 min IMPERVIOUS AREA
ABSTRACTION COEFF: 0.20 AREA. . : 1. 00 Acres
CN. . . . . 98 .00
' TcReach - Sheet L: 200. 00 ns: 0.0110 p2yr: 2 .00 s:0. 0100
TcReach - Shallow L: 80.00 ks: 11. 00 s:0.0100
PEAK RATE: 0. 62 cfs VOL: 0. 23 Ac-ft TIME: 480 min
BASIN ID: PRE NAME: 10-YEAR PREDEVELOPED STORM
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 1. 07 Acres BASEFLOWS: 0.00 cfs
RAINFALL TYPE. . . . : TYPEIA PERVIOUS AREA
' PRECIPITATION. . . . : 2 .90 inches AREA. . : 1.03 Acres
TIME INTERVAL. . . . : 10. 00 min CN. . . . : 86.83
TIME OF CONC. . . . . : 21.80 min IMPERVIOUS AREA
ABSTRACTION COEFF: 0.20 AREA. . : 0. 04 Acres
CN. . . . : 98. 00
TcReach - Sheet L: 200. 00 ns: 0. 1500 p2yr: 2. 00 s: 0. 0225
TcReach - Shallow L: 80. 00 ks: 11. 00 s: 0. 0100
PEAK RATE: 0. 32 cfs VOL: 0. 15 Ac-ft TIME: 480 min
1
' 2/23/95 Warner Engineering page 1
RENTON MAZDA
PRELIMINARY STORM ANALYSIS
PREPARED BY: C. LEVEY
' BASIN SUMMARY
BASIN ID: POST NAME: 100-YEAR POSTDEVELOPED STORM
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 1. 07 Acres BASEFLOWS: 0. 00 cfs
' RAINFALL TYPE. . . . : TYPEIA PERVIOUS AREA
PRECIPITATION. . . . : 3. 90 inches AREA. . : 0. 08 Acres
TIME INTERVAL. . . . : 10.00 min CN. . . . : 86.00
' TIME OF CONC. . . . . : 4 . 73 min-- IMPERVIOUS AREA
ABSTRACTION COEFF: 0. 20 AREA. . : 1. 00 Acres
CN. . . . . 98.00
' TcReach - Sheet L: 200.00 ns: 0.0110 p2yr: 2 . 00 s:0. 0100
TcReach - Shallow L: 80. 00 ks: 11.00 s: 0. 0100
PEAK RATE: 0. 85 cfs VOL: 0.32 Ac-ft TIME: 470 min
BASIN ID: PRE NAME: 100-YEAR PREDEVELOPED STORM
' SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 1. 07 Acres BASEFLOWS: 0. 00 cfs
RAINFALL TYPE. . . . : TYPEIA PERVIOUS AREA
' PRECIPITATION. . . . : 3 .90 inches AREA. . : 1. 03 Acres
TIME INTERVAL. . . . : 10. 00 min - CN. . . . : 86.83
TIME OF CONC. . . . . : 21.80 min IMPERVIOUS AREA
ABSTRACTION COEFF: 0.20 AREA. . : 0. 04 Acres
' CN. . . . : 98. 00
TcReach - Sheet L: 200. 00 ns: 0. 1500 p2yr: 2 .00 s: 0. 0225
TcReach - Shallow L: 80. 00 ks: 11. 00 s:0.0100
' PEAK RATE: 0.51 cfs VOL: 0. 23 Ac-ft TIME: 480 min
1
1 2/23/95 Warner Engineering page 1
RENTON MAZDA
PRELIMINARY STORM ANALYSIS
PREPARED BY: C. LEVEY
--------------
BASIN SUMMARY
1 BASIN ID: POST NAME: WATER QUALITY STORM 0. 33P2
SBUH METHODOLOGY
1 TOTAL AREA. . . . . . . : 1.07 Acres BASEFLOWS: 0. 00 cfs
RAINFALL TYPE. . . . : TYPElA PERVIOUS AREA
PRECIPITATION. . . . : 0.66 inches AREA. . : 0. 08 Acres
TIME INTERVAL. . . . : 10. 00 min CN. . . . : 86.00
1 TIME OF CONC. . . . . : 4.73 min IMPERVIOUS AREA
ABSTRACTION COEFF: 0.20 AREA. . : 1.00 Acres
CN. . . . . 98 .00
1 TcReach - Sheet L: 200. 00 ns:0.0110 p2yr: 2 . 00 s:0. 0100
TcReach - Shallow L: 80. 00 ks: 11.00 s: 0. 0100
PEAK RATE: 0. 11 cfs VOL: 0.04 Ac-ft TIME: 480 min
AA- &
1 _ 4
zs1 � C 5
1 jq s��akDz a, o zs(ca
Fyn ok. �Qj, Af z 2S , 6 �•
1 W.t, Vo1J'"' _ I -? ,qZ
Vol
A� xt-V1 } 174 w/
..I.l.._
1 P. 6(C
' SW 12th St. Pipe - 10 yr Storm
Worksheet for Circular Channel
' Project Description
Project File untitled
' Worksheet Sound Mazda
Flow Element Circular Channel
Method Manning's Formula
' Solve For Channel Depth
' Input Data
Mannings Coefficient 0.012
Channel Slope 0.002700 fUft
' Diameter 12.00 in
Discharge 1.24 fP/s
' Results
Depth 0.57 ft
Flow Area 0.46 ft'
' Wetted Perimeter 1.71 ft
Top Width 0.99 ft
Critical Depth 0.47 ft
' Percent Full 56,89 %
Critical Slope 0.005109 ftlft
Velocity 2.69 f/S
' Velocity Head 0.11 ft
Specific Energy 0.68 ft
Froude Number 0.69
' Maximum Discharge 2.16 ft3/s
Full Flow Capacity 2.01 ft3/s
Full Flow Slope 0.001032 ft/ft
' Flow is subcritical.
1
Sap 18,1995 Warner Engineering FlowMaster v4.1
' 08'05'17 Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page 1 of 1
SW 12th St. Pipe - 100 yr Storm
Worksheet for Circular Channel
Project Description
Project File untitled
' Worksheet Sound Mazda
Flow Element Circular Channel
Method Manning's Formula
' Solve For Channel Depth
' Input Data
Mannings Coefficient 0.012
Channel Slope 0.002700 ft/ft
Diameter 12.00 in
' Discharge 1.70 fN/s
Results
Depth 0.71 ft
Flow Area 0.59 ft'
' Wetted Perimeter 2.00 ft
Top Width 0.91 ft
Critical Depth 0.55 ft
' Percent Full 70.67 %
Critical Slope 0,005512 ft/ft
Velocity 2.86 ft/s
' Velocity Head 0.13 ft
Specific Energy 0.83 ft
Froude Number 0.63
' Maximum Discharge 2.16 ft3/s
Full Flow Capacity 2.01 ft'/s
Full Flow Slope 0.001940 tt/ft
' Flow is subcritical.
Sep 18, 1995 Warner Engineering FlowMaster v4.1
08:04:44 Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page i of 1
BuildingAPPENDIX H
King County and Land Development Division
TECHNICAL INFORMATION ' • ' WORKSHEET
R :
'PART1�-PROJECT.OWNERAND= „�` = � PART2��pROJECTLOCATtON` 1��
- :::AND DESCRIPTIONz` ` '
Address � • py�Ah��, Location
RangePhone Township
Company
• Section
UpstreamDrainage Basin Size 0"—AC
R
7FE�mmercial
PART4 OTHERPERdIli D• Shoreline _•-
Grading DOEDamSafety Structural Vaults
Other
O Other COEWetlands
PARTS-'SITECOMMUNITYANDDRAIHAGEBASIN ;�'.
Community
r
Drainage
Basin G<P-04\
0 River
Floodplain
F-� Stream Wetlands
CD Critical Stream Reach Seeps/Springs
Depress .
Lake Groundwater�•echarge
• _
Lake .-/E ros ion Hazard
�PART7TVM/`17� iTy��CY.k� F,'i';r`�.ss.}�.•a y3f.f�tY��•S S y-t < r Ry � 43�r^S'�-Xx f :5 Nr "s�l� 4✓Soil Type
.� .sa...�'_1� Lyc. ..s ..5"+.2a~k.5,.��zfri,.y-{Y:s.:.L t.e:_n k.. �'a..A��"�w'Tr :'�:i�i.'• -
Erosion Potential
I•
' Pago 2 of 2
King County Building and Land Development Division
' TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
' REFERENCE LIMI1TATION/SITECONSTRAINT� (_
(] Ch.4 -Downstream Analysis_ NoYI•e�r �✓ �i�tF� Tu'� Zit_5.- {oY..-,.-
O —
0
' F--� Additional Sheets Attatched
MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS
pURING CONSTRUCTION FOLLOWING CONSTRUCTION
Sedimentation Facilities Stabilize Exposed Surface
Stabilized Construction Entrance Q Remove and Restore Temporary ESC Facilities
' EkT Perimeter Runoff Control Co Clean and Remove All Silt and Debris I
O ,Clearing and Grading Restrictions EO� Ensure Operation of Permanent Facilities
' �over Practices EJ Flag Limits of NGPES
2 Construction Sequence (] Other
Other
C., ) Grass Lined Channel = Tank 0 Infiltration Method of Analysis
' ipe System = Vault Depression
L.J( Open Channel Energy Dissapalor ;_] Flow Dispersal Compensation/Mitigation
Dry Pond 0 Wetland - Waiver of liminated Site Storage
(� Wet Pond Stream O�y Regional Detention
Brief Description of System0peration cpv)e� ATE WINO- JN Vjo ktNS
ows ,) ter >.� o-0W w�,k� : cif- o c;�Cy �arn.
— — — a J
- Facility Rolal d Site Limitations t'''y � Additional Sheets Attatched
Reference Facility Limitation
t — -- --- - — �: wqR
c. co `
• z
[] Drainage Easement g,A
' Q ast in Place Vaull Othe-r,,,,�1 t � Access Easement t°: •a\ 16157
4 Retaining Wall Native Growth Pro
fecti�n t'ftiRi
�) Rockery > 4'High [] Tract ` °5101 G
' [_] Structural on Sloop Slope i I j Other I
---- - ----- _ . . . - --. , - - - Ftftks-9/21
y7-
' j 1 or a civil ongineor under my suporvision have visited the silo Ac ua1
site conditions as observed were incorporated into this worksheei and the yC ��.. S,�J.��• `21.- ��tjlq,
I. anatehments. To the best of my knowledge the information provided
j horn is accurate.
APPENDIX I
Creative Engineering Options INC.
C�v
A firm practicing in the geosciences
' PREPARED FOR
—� SOUND MAZDA
GEOTECHNICAL ENGINEERING STUDY
PROPOSED SOUND MAZDA FACILITY
RAINIER AVENUES. AT
SOUTH GRADY WAY
RENTON, WASHINGTON
s�
N MA
G�o WA4&
P
y z
Glen(*nn, P. o,c� �FcrsrExxE°
President ' SSSrOfVALEjG
EXPIRES I a Irf
941550
February 6, 1995
fiI Copyright Creative Engineering Options, Inc. February 6, 1995.
_L
5418 1 59th Place NE • Redmond, WA 98052 • 1206) 883-6889 • (206) 953-1 173 • FAX 867-9664
` Creative Engineering Options INC.
GO
A firm practicing in the geosciences
February 6, 1995 94-623
Sound Mazda
c/o Mr. Scott E. Anderson
Anderson & Boone Architects
525 Columbia Street N.W.
Suite 201
Olympia, Washington 98501
Gentlemen:
We are pleased to submit herewith our report entitled "Geotechnical Engineering Study,
—� Proposed Sound Mazda Facility, Rainier Avenue South at South Grady Way, Renton,
Washington". The primary purposes of this study were to evaluate the nature of the
subsurface conditions beneath the site, and to provide geotechnical recommendations for
site development.
The opinions and recommendations contained in this report are based on the information
made available to us at the time of writing, and developed from our data review, field
observations, and our engineering analyses. We proceeded with our services on the
basis of Mr. Anderson's December 12, 1994 written authorization.
In our professional opinion, based on the results of this study, it is geotechnically feasible
to construct the proposed building and appurtenances generally as planned. The
proposed structure(s) may be supported on conventional spread footings bearing on
either the re-densified native soils or, if appropriate, on a compacted structural fill pad.
All foundations are expected to be set at depths of at least eighteen (18) inches below
existing grade.
In general, providing the recommendations for site preparation and general earthwork are
■, closely followed, both the re-densified in-place soils and any new compacted structural
■7 fills should be sufficiently competent to support a concrete slab-on-grade floor system.
They should also be expected to be capable of supporting a typical asphalt parking lot
.� pavement.
The presence of organic silt and peat was noted at relatively shallow depth beneath part
of the site (Test Pits 4 and 5). These materials are unsuitable for load support and will
need to be overexcavated and removed.
5418 1 59th Place NE - Redmond, WA 98052 - 1206i 883-6889 - l2061 953-1 1 73 " FAX 867-9664
The in-place density or consistency of the soils encountered on this site appears to
increase with depth, and the shallow unsuitable organic soils are expected to be
overexcavated and removed. In addition, there appears to be a lack of a shallow water
level that might surge during an earthquake. Thus, we do not believe the in-situ soils are
likely to be at significant risk of liquefaction or severe settlement under the affects of a
seismic event on the order of 6.8 on the Richter scale, or less.
The majority of the on-site materials, although containing some organic silts and peats
as well as varying amounts of silt sized particles, appear to be generally suitable for re-
use as a structural fill. However, they must be free of organics and other deleterious
material, and must be placed and compacted in strict accordance with the recom-
mendations contained in this report.
We appreciate the opportunity to provide this service and look forward to working with you
during the construction phase of this project. Should you have any questions regarding
this report, please call.
Very truly yours,
CREATIVE ENGINEERING OPTIONS, INC.
1�
Glen Mann, P.E.
President
gm/Soundmaz.Rpt/eb21
- 2 -
IMPORTANT INFORMATION i •
ENGINEERING REPORT
As the client of a consulting geotechnical engineer,you MOST GEOTECHNICAL FINDINGS ARE
should know that site subsurface conditions cause more PROFESSIONAL JUDGMENTS
construction problems than any other factor.ASFF/rhe Site exploration identifies actual subsurface conditions
Association of Engineering Firms Practicing in the only at those points where samples are taken.The data
Geosciences offers the following suggestions and were extrapolated by your geotechnical engineer who
observations to help you manage your risks. then applied judgment to render an opinion about
overall subsurface conditions.The actual interface
A GEOTECHNICAL ENGINEERING REPORT IS BASED between materials may be far more gradual or abrupt
ON A UNIQUE SET OF PROJECT-SPECIFIC FACTORS than your report indicates.Actual conditions in areas
Your geotechnical engineering report is based on a not sampled may differ from those predicted in your
subsurface exploration plan designed to consider a report.While nothing can be done to prevent such
unique set of project-specific factors.These factors situations,you and your geotechnical engineer can work
typically include:the general nature of the structure together to help minimize their impact.Retaining your
involved,its size,and configuration;the location of the geotechnical engineer to observe construction can be
structure on the site;other improvements,such as particularly beneficial in this respect.
access roads,parking lots,and underground utilities;
and the additional risk created by scope-of-service A REPORT'S RECOMMENDATIONS
limitations imposed by the client.To help avoid costly CAN ONLY BE PRELIMINARY
problems,ask your geotechnical engineer to evaluate The construction recommendations included in your
how factors that change subsequent to the date of the geotechnical engineers report are preliminary,because
report may affect the report's recommendations. they must be based on the assumption that conditions
revealed through selective exploratory sampling are
Unless your geotechnical engineer indicates otherwise, indicative of actual conditions throughout a site.
do not use your geotechnical engineering report: Because actual subsurface conditions can be discerned
only during earthwork,you should retain your geo-
■ when the nature of the proposed structure is technical engineer to observe actual conditions and to
changed,for example,if an office building will be finalize recommendations.Only the geotechnical
erected instead of a parking garage,or a refrigerated engineer who prepared the report is fully familiar with
warehouse will be built instead of an unrefrigerated the background information needed to determine
one; whether or not the report's recommendations are valid
■ when the size,elevation,or configuration of the and whether or not the contractor is abiding by appli-
proposed structure is altered; cable recommendations.The geotechnical engineer who
�I • when the location or orientation of the proposed developed your report cannot assume responsibility or
�■JIII structure is modified; liability for the adequacy of the report's recommenda-
■ when there is a change of ownership;or tions if another party is retained to observe construction.
■ for application to an adjacent site.
GEOTECHNICAL SERVICES ARE PERFORMED
Jul Geotechnical engineers cannot accept responsibility for FOR SPECIFIC PURPOSES AND PERSONS
problems that may occur if they are not consulted after Consulting geotechnical engineers prepare reports to
factors considered in their report's development have meet the specific needs of specific individuals.A report
changed. prepared for a civil engineer may not be adequate for a
construction contractor or even another civil engineer.
SUBSURFACE CONDITIONS CAN CHANGE Unless indicated otherwise,your geotechnical engineer
�I A geotechnical engineering report is based on condi- prepared your report expressly for you and expressly for
tions that existed at the time of subsurface exploration. purposes you indicated. No one other than you should
Do not base construction decisions on a geotechnical apply this report for its intended purpose without first
engineering report whose adequacy may have been conferring with the geotechnical engineer.No party
affected by time.Speak with your geotechnical consult- should apply this report for any purpose other than that
ant to learn if additional tests are advisable before originally contemplated without first conferring with the
construction starts.Note,too,that additional tests may geotechnical engineer.
be required when subsurface conditions are affected by
construction operations at or adjacent to the site,or by GEOENVIRONMENTAL CONCERNS
natural events such as floods,earthquakes,or ground ARE NOT AT ISSUE
water fluctuations.Keep your geotechnical consultant Your geotechnical engineering report is not likely to
apprised of any such events. relate any findings,conclusions,or recommendations
about the potential for hazardous materials existing at mates was not one of the specific purposes for which it
' the site.The equipment,techniques,and personnel was prepared. In other words,while a contractor may
used to perform a geoenvironmental exploration differ gain important knowledge from a report prepared for
substantially from those applied in geotechnical another party,the contractor would be well-advised to
' engineering.Contamination can create major risks.If discuss the report with your geotechnical engineer and
you have no information about the potential for your to perform the additional or alternative work that the
site being contaminated,you are advised to speak with contractor believes may be needed to obtain the data
your geotechnical consultant for information relating to specifically appropriate for construction cost estimating —
' geoenvironmental issues. purposes.)Some clients believe that it is unwise or
unnecessary to give contractors access to their geo-
A GEOTECHNICAL ENGINEERING REPORT IS technical engineering reports because they hold the
SUBJECT TO MISINTERPRETATION mistaken impression that simply disclaiming responsi-
' Costly problems can occur when other design profes- bility for the accuracy of subsurface information always
sionals develop their plans based on misinterpretations insulates them from attendant liability.Providing the
of a geotechnical engineering report.To help avoid best available information to contractors helps prevent
misinterpretations,retain your geotechnical engineer to costly construction problems.It also helps reduce the
' work with other project design professionals who are adversarial attitudes that can aggravate problems to
affected by the geotechnical report. Have your geotech- disproportionate scale.
nical engineer explain report implications to design
' professionals affected by them,and then review those READ RESPONSIBILITY CLAUSES CLOSELY
design professionals'plans and specifications to see Because geotechnical engineering is based extensively
how they have incorporated geotechnical factors. on judgment and opinion,it is far less exact than other
Although certain other design professionals may be fam- design disciplines.This situation has resulted in wholly —
' iliar with geotechnical concerns,none knows as much unwarranted claims being lodged against geotechnical
about them as a competent geotechnical engineer. engineers.To help prevent this problem,geotechniall
engineers have developed a number of clauses for use In
BORING LOGS SHOULD NOT BE SEPARATED their contracts,reports,and other documents.Responsl-
' FROM THE REPORT bility clauses are not exculpatory clauses designed to
Geotechnical engineers develop final boring logs based transfer geotechnical engineers'liabilities to other
upon their interpretation of the field logs(assembled by parties.Instead,they are definitive clauses that identify
site personnel)and laboratory evaluation of field where geotechnical engineers responsibilities begin and —
samples.Geotechnical engineers customadly include end.Their use helps all parties involved recognize their
only final boring logs in their reports. Final boring logs individual responsibilities and take appropriate action.
should not under any circumstances be redrawn for Some of these definitive clauses are likely to appear in —
inclusion in architectural or other design drawings, your geotechnical engineering report. Read them
because drafters may commit errors or omissions in the closely.Your geotechnical engineer will be pleased to
transfer process.Although photographic reproduction give full and frank answers to any questions.
eliminates this problem,it does nothing to minimize the
possibility of contractors misinterpreting the logs during RELY ON THE GEOTECHNICAL ENGINEER
bid preparation.When this occurs,delays,disputes,and FOR ADDITIONAL ASSISTANCE
unanticipated costs are the all-too-frequent result. Most ASFE-member consulting geotechnical engineer-
ing firms are familiar with a variety of techniques and
' To minimize the likelihood of boring log misinterpreta- approaches that can be used to help reduce risks for all
tion.give contractors ready access to the complete parties to a construction project,from design through
geotechnical engineering report prepared or authorized construction.Speak with your geotechnical engineer not
' for their use.(If access is provided only to the report only about geotechnical issues,but others as well,to
prepared for you,you should advise contractors of the learn about approaches that may be of genuine benefit.
reports limitations,assuming that a contractor was not You may also wish to obtain certain ASFE publications.
one of the specific persons for whom the report was Contact a member of ASFE of ASFE for a complimentary
' prepared and that developing construction cost esti- directory of ASFE publications.
THE ASSOCIATION
OF ENC4NEERING
A S F E PRACTICING INTHERkU GEOSCIENCES
' 8811 COLESVILLE ROAD/SUITE G106fSILVER SPRING,MD 20910
TELEPHONE:301/565-2733 FACSIMILE: 301/589-2017
' Copyrlght 1992 by ASFE,Inc unless ASFE grants specific permission to do so,duplication of this document by any means whatsoever is expressly prohibited
Reuse of the wording in this document.In whole or In part.also is expressly prohibited,and may be done only with the express permission of ASFE or for purposes
of review or scholarly research.
8P00592A/1.5M
1
TABLE OF CONTENTS
94-1550
PAGE
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Project Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Scope of Services . 2
SITE CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Surface 5
Subsurface r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Groundwater 6
DISCUSSION AND RECOMMENDATIONS : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 8
General a
Site Preparation ....General Earthwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
- General 9
- Demolition . 9
- Stripping and Clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • • . . . . 9
- Overexcavation 10
- Excavations and Slopes 10
Proofr
- Re-De sific ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
- Re-Densification 12
- Structural Fill . . 12
- Fill Placement and Compaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
- Utility Trench Fill . 13
- Fill Source Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
- In-Situ Density Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Foundations 15
- General . . 15
- Conventional Foundation Design Parameters . 16
- Settlement . . Found . . . . . . . . . . . . . . mete . . . . . . . . . . . . . . . . . . . . . 17
- Lateral Load Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Buried or Basement and Retaining Walls . . . . . . . . . . . . . . . . . . . . . . . . . . 19
-� i
S 19
Seismic Risk . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . .Slab-on-Grade Floors . . . . . . . • • . 20
Liquefaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Site Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
. . . . . . . . . . . .
- General 22
- Short Term Drainage Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
- Long Term Drainage Measures 23
- Roof Drainage . 24
- Erosion Hazard 24
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
- Erosion Control . 24
Pavement Areas 25
- General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
- Subgrades . 25
Pavement Sections 26
Roadway Base Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
CLOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Limitations . . . . . . . . . . . . . . . 29
Additional Services . . . . . . . . . . . . . 29
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
- Plan and Specification Review 29
- Pre-Construction Meeting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
- Construction Monitoring and Testing . . . . . . . . . . . . . . . . . . . . . . . . . 30
APPENDIX A - Field Exploration Program
APPENDIX B - Laboratory Testing Program
- ii -
7
�l
�l
ILLUSTRATIONS
—�- 94-1550
' Plate 1 Vicinity Map
—� Plate 2 Site Plan
Plate 3 Typical Utility Trench Fill
Plate 4 Structural Fill Pad Detail
Plate 5 Foundation Support Detail
Plate 6 Wall and Footing Drain Detail
Plate 7 Typical Filter Fence Detail
Plate S Legend
Plates 9 through 13 Test Pit Logs
' Plate 14 Gradation Curve
GEOTECHNICAL ENGINEERING STUDY
PROPOSED SOUND MAZDA FACILITY
RAINIER AVENUE SOUTH AT SOUTH GRADY WAY
RENTON, WASHINGTON
94-1550
INTRODUCTION
General
As requested, this report summarizes the results of our geotechnical engineering study
of the project. The project incorporates either a pre-fabricated metal or a concrete
masonry block building surrounded by asphalt pavement which is to become a motor
vehicle sales and service facility. We proceeded with our services on the basis of Mr.
Anderson's December 12, 1994 written authorization. The site is located on the western
side of Rainier Avenue South and immediately south of South Grady Way, just north of
the junction with SR-405, in Renton.
The primary purposes of our study will be to explore and characterize the site's
subsurface soil and groundwater conditions to help determine the in-situ nature and
general stratigraphy of the underlying materials. The results of our study acted as a basis
for formulation of geotechnical recommendations for design and construction of building
foundations, site preparation and earthwork operations, fill placement and compaction,
and site drainage and erosion control measures.
The site is located approximately as shown on the Vicinity Map, Plate 1 . The general
layout of the project is presented on the attached Site Plan, Plate 2. This site plan also
■ shows the approximate locations of the exploratory test pits. This report addresses the
nJ geotechnical aspects of site development only. It does not address any environmental
aspects of the site conditions, such as the potential presence of toxic or hazardous
conditions or buried tanks. If required, environmental aspects of site development should
be addressed in a separate report.
fiProiect Description
We understand from our discussions with Mr. Boone that the current intent is to develop
this property by constructing either a prefabricated metal structure or a concrete masonry
block building to house a sales office and, possibly, a workshop. In either case
the building is expected to use a concrete slab-on-grade floor system.
_J
I
V
i1NS V y crxrrR y S = iE4TH
� w
�N VA J
2 Sw rN CT vQ ;M '^ J
BN I a f� ` s p1. S ��. STH 3 ST s
f ~ J 5'
EA L
RR v SCUM '� s
q (= uaRrrr.
SW 7TH s4 S S H ST Pr o�o �y 6T511 s
AA
{ _ i PARK iw `t z
6 RIDE G�,Q
5A N ENTDN VILLAGE
I H ST tin AoY W� 3F CENTER
o SW 1 N` ;g S R ON VILLAGE PL
,atH 5T HDLIDAY
R
N APPROXIMATE
¢' SITE LOCATION 2 m
(n
fN(C 5(R .. � r
SW I �116TH I ST SW 2 PARK 5 15TH
�I '<I 400 161-H ST o F y s " S 16TH ST
I t o LOW cFALWr S 18TH FL ��
Ir
a 1 SW 19TH ST ;ram n $ ST O
LONGACRfS L-Lj I L 1 S 19TH ST TALBOT i
20 r` HILL I
t� I RACE � t� c4 Pt PARK
SW 21ST ST
I TRACK 1 r
3 gzNo I
1
i N SW 23RD ST _ S _23RD 3; ST ;
CALSOKLE
,r5
I t W PARK r $
ATN
Reference: Thomas Brothers Maps, 1995 edition
of King County, Map No.656,Grid BL.
1 $ N
Creative Engineering Options wc. Plate
@v VICINITY MAP
" AP"'"�°'Q'9"tlHGwu�� Sound Mazda �
a
�f•• 1 log �
TLP-22
u � •1,
ILI
.ram.�; ._,t�TA,-7• ,� '.; ' R+ "'. ~�''•
s:
n .�
.�!!K• ��11 " a 1 �t ` 1 !� 'f`//,+,tip ��' _ t
LEGEND
®TP-9 Number and approximate location of
Reference: Preliminary Site Plan by Anderson 3 exploratory boring excavation
Boone Architects,undated.
N Approingximate location of proposed
build
Creative Engineering Options INC Plate
Ccv SITE PLAN
i Sound Mazda 2
Geotechnical Engineering Study Page 2
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
Although no specific design data are currently available to us, based on our experience
with similar commercial construction we estimate that the building's maximum combined
dead plus live loads are likely to be on the order of the following:
■ Vertical (axial) column load = 55 kips
■ Horizontal column load = 15 kips
(Prefabricated metal building)
■ Wall load = 2 to 3 kips per
(CMU building) linear foot
■ Floor load = 250 psf
Excavation work is expected to be limited to that necessary for foundation construction
and utility trench installation. We estimate that such excavation should not be more than,
about two to four feet deep. To the best of our knowledge no on-site structural fills are
planned at this time. The majority of the area surrounding the structure, which is
expected to be centrally located on the site, is to be asphalt paved vehicle parking (show)
lot.
Scope of Services
Our scope of services, developed from our discussions with Mr. Boone and our
experience on similar property, is designed to obtain as much subsurface information from
the site as possible within the necessary access, time and budgetary constraints. More
specifically, our scope includes the following:
■ Performance of a limited subsurface exploration to characterize
the site soil and groundwater conditions by means of a series of
exploratory excavations,
Geotechnical Engineering Study Page 3
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
.� ■ Performance of a limited geotechnical laboratory testing program
including, but not necessarily limited to, moisture content, grain
size analyses, and plasticity limits,
■ Performance of appropriate geotechnical engineering analyses to
help determine the potential geotechnical design criteria,
■ Provision of geotechnical recommendations for site earthwork and
grading, including overexcavation, fill placement and compaction,
and utility trench excavation and backfilling,
■ Provision of geotechnical recommendations for design and cons-
truction of conventional spread footings, including allowable soil
bearing pressure and resistance to lateral loads, and a vertical
i, subgrade modulus for floor slab design
■ Provision of geotechnical recommendations for design and cons-
truction of below grade and/or retaining walls, including lateral
loads and frictional resistance,
_1
■ Provision of an estimate of the potential magnitudes of total and
^' differential settlement, and the approximate rates at which they
occur, under the proposed building loads,
■ Evaluation of the site's potential for liquefaction under seismic
conditions, and of the seismic history, including an appropriate
seismic acceleration value,
■ Provision of geotechnical recommendations for short and long
term site drainage control measures and for site erosion control,
■ Provision of geotechnical recommendations for design pavement
sections for light traffic support, and
1
Geotechnical Engineering Study Page 4
1 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
1 ■ Provision of four copies of a written final report summarizing
the above information.
1
This report has been prepared for specific application to this proposed Sound Mazda
1 Sales and Service facility project at Rainier Avenue South and South Grady Way in
Renton only, and is for the exclusive use of Sound Mazda and their other representatives,
1 consultants and contractors. No other warranty, expressed or implied, is made. We
recommend that this report, in its entirety, be made readily available for the contractor(s)
information and estimating purposes. However, provision of this report to the contractor
1 should not be considered a sufficient reason for the contractor not to perform his own site
study.
1 Our work on this project will be performed in general accordance with the above scope
of services and the General Conditions (attached to our proposal).
1 Our geotechnical recommendations, based on our data review, site observations, and
engineering analyses, are presented following the discussion of site conditions. A more
detailed account of the field exploration program, along with the Test Pit logs, is included
1 as Appendix A to this report. A general description of the geotechnical laboratory testing
program, with the appropriate test data sheets, is presented in Appendix B.
1 �
1 �
1
1 -
1
1
i
1
Geotechnical Engineering Study Page 5
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
SITE CONDITIONS
Surface
The site is located on the western side of Rainier Avenue South and immediately south
of South Grady Way, just north of the junction with SR-405 in Renton, Washington (see
Plate 1). The site is bounded to the south by S.W. 12th Street, and to the west by
existing single family residences.
Overall, the site is relatively flat and level though it slopes gently down to the south and
west from the adjacent street levels. Based on our visual evaluation of the site we
estimate that the topographic change across the site is on the order of about six to eight
feet. There is currently a steel pile mounted advertising sign located in the northeast
corner of the property. There are six steel piles extending to an undetermined depth
supporting this sign. A large part of the site surface is covered with gravel to create a
"paved" surface on which new automobiles are currently being stored.
At the time of our field visit, we observed visible evidence of several areas of shallow
standing water on the property. These "pools" appear to be localized ares of "potholing"
-� in the site surface most likely caused by automobile traffic and are typically only about
two to three inches deep. Since our site work was performed after a period of prolonged
precipitation it is our expectation that they should dry out relatively quickly.
Subsurface
a� The site was explored by excavation of a total of nine exploratory test pits located around
the site. The approximate test pit locations are shown on the Site Plan, Plate 2. The test
pit logs are included in Appendix A to this report and provide more detailed descriptions
of the soils encountered at each location explored. The following is a generalized
description of the subsurface conditions encountered in our study.
Portions of the site surface (Test Pits 2, 3, 5, 8 and 9) are covered with a thin surficial
layer of sod and topsoil which we have classified as an OL in general accordance with
the Unified Soil Classification System (USCS). Typically, this layer is about six to twelve
(12) inches thick. The remainder of the site is covered with either a thin layer of crushed
rock (Test Pits 4, 6 and 7) classified by the USCS as a GM or GP, or a silty sand fill
containing pieces of brick, gravel, broken sandstone and an occasional boulder classified
as an SM by the USCS. These materials vary between about twelve (12) and eighteen
(18) inches and three feet in thickness, respectively. In Test Pits 1 and 5 through 8 the
6�
' Geotechnical Engineering Study Page 6
' 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
r.
surficial soils are considered to possibly constitute a surficial fill. This fill, if this is the
case, extends to a depth of between approximately two and one half and three feet.
Beneath the surficial layer we encountered similar conditions in all of the excavations
except for Test Pits 4 and 5 which included a shallow layer of organic silt and/or peat. -
' The soils consist predominantly of interlayered medium dense silty sands(SM) and sandy
silts (ML) extending to depths of between approximately six and seven feet below the
existing grade. Beneath this we found either a medium dense fine to coarse sand (SP)
' with gravel lenses or a gravel (GP). The deeper test pits were terminated within these
coarse granular deposits.
' As indicated above, a layer of soft and potentially compressible material was encountered `
in Test Pits 4 and 5. In the former the layer consists of a medium dense silt with roots iE
matter and is described as a "Topsoil". It extends from a depth of about one foot to
' about two feet below the existing grade and is classified as an OL by the USCS. In Test
Pit 5 there is a layer of soft fibrous Peat, which includes small pieces of coal, at a depth
t of about two and one half feet. This material, which is classified by the USCS as a Pt,
is approximately eighteen (18) inches thick.
' With the exception of the surficial topsoil and the shallow organic sift and peat materials,
all of the soils encountered at this site, although containing a large proportion of fine
grained materials, are generally granular in nature. If adequately re-densified, and
' reasonably dry, they should be capable of providing a competent bearing surface. Also
when re-densified, these soils are unlikely to undergo any significant settlement under
load. They are also considered competent to support concrete floor slabs and asphalt
t pavement sections providing they are treated as described in this supplemental report.
Because of the relatively large amount of "moisture sensitive" sift in these soils they are
likely to become easily disturbed when wet, and tend to present difficulties in earthwork
operations during the wetter winter months. Because of their sift content these soils are
often relatively slow draining, typically exhibiting permeability ratings of less than two
inches per hour.
' Groundwater
' In spite of the fact that our field exploration was performed after several days of sustained
and relatively heavy precipitation, we found no visible evidence of an established
' groundwater level within the depth of exploration. However, we did observe some light
groundwater seepage in three of the excavations at the time of the field study. The
seepage occurs between depths of approximately six and eight feet and appears to be
lot
Geotechnical Engineering Study Page 7
95-1550 Sound Mazda Sales and Service Facility g
February 6, 1995
from within either a clean sand layer (Test Pit 5) or from gravel lenses within sandy
materials (Test Pits 7 and 9).
It has also been our experience that groundwater and seepage levels should not be
considered static. Typically, fluctuations in the levels and rate of flow can, and often do,
occur on a seasonal basis, after periods of heavy or sustained precipitation, or from
surface flow from elsewhere on the property or its surroundings. Any potential earthwork
contractor should be aware of this and should take appropriate measures in his bid by
including a contingency in his budget and schedule to accommodate the potential problem
of shallow groundwater or seepage at construction.
' Geotechnical Engineering Study Page 8
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
' DISCUSSION AND RECOMMENDATIONS
' General
' Based on the results of our study, it is our professional opinion that it is geotechnically
feasible to develop this site and construct the proposed building(s) generally as planned.
' The building(s) may be supported on conventional spread footings bearing on either the
thoroughly re-densified in-place soils at relatively shallow depth or, if preferred, on at least
two feet of compacted structural fill (described later in this report).
' Similarly, once the potentially compressible organic soils have been overexcavated and
removed, the thoroughly re-densified in-situ soils should also be exp=.ed to be capable
' of supporting both a concrete slab-on-grade floor system and an asphalt pavement
without significant detriment. However, it is important that the subgrade is treated as
described herein to achieve this performance.
' From our examination of the site conditions, and the apparent competency of the majority
of the in-place site soils, it is our opinion that once the subgrade has been thoroughly re-
' densified (as described later in this report) the building area should be subject to little
settlement under the proposed building loads, providing the soils are treated as described
later in this report.
' The generally non-plastic subsurface soils encountered are, typically, in a medium dense
condition. It also appears that the site groundwater level, that could surge and cause
' saturation of the surficial soils, is well below the site subgrade elevation. Given these
conditions, and considering that the site soils are to be thoroughly re-densified, it is our
professional opinion that these soils are, in general, unlikely to be subject to any
' significant liquefaction should a seismic event of relatively high magnitude occur.
The majority of the in-place soils appear to be generally suitable for re-use as a structural
' fill elsewhere on the site. However, if they are to be used for this purpose they must be
free of organics and other deleterious materials, and must be within three points of the
materials' optimum moisture content.
' These and other geotechnical aspects of the project are discussed in more detail in the
following sections of this report.
1
1
Geotechnical Engineering Study Page 9
■, 95-1550 Sound Mazda Sales and Service Facility
■JI February 6, 1995
_J Site Preparation and General Earthwork
General: Based on our discussions with the architect, and the results of our study, we
believe that the proposed construction is geotechnically feasible provided that our
recommendations are carefully followed. Although no significant excavation work is
anticipated,the following paragraphs describe the various elements of the site preparation
and general earthwork phases of site development.
Demolition: Before any stripping or clearing can be performed it will be necessary to
demolish and remove the existing advertising structure on this site. This will include the
removal of the below grade portions of the steel pile sign supports.
Failure to remove all of the partially to completely buried strums Ural elements could result
in the development of one, or more, "hard spots". These are locations where the buried
structural elements are more resistant to compression and/or settlement that the
surrounding soils. In these areas it is possible for the new pavements to "settle" around
the "hard spot" which can result in structural damage, and should be avoided.
Stripping and Clearing: The surface of all the development areas should be stripped
and cleared of all surface vegetation, trees, shrubs, topsoil, organic matter, unsuitable
surficial fill materials, and any other deleterious material. We estimate that an average
overall stripping depth of about eight inches is likely to be required. However, since there
are large areas of the property that were not subject to direct in-place exploration it is
possible that greater thicknesses of unsuitable topsoil or uncontrolled fill material may
exist in some locations on the site. Because of this, we recommend that the owner
provide a contingency in the budget and schedule to accommodate this risk.
Stripped materials should be removed from the site and disposed in accordance with the
applicable local regulations. However, if the topsoil is suitable, it may be stockpiled for
later use in landscaping, if desired. The stripped material should not be mixed with any
materials to be used as structural fill.
We also recommend that, as a precautionary measure, any stockpiled material be kept
a minimum distance of fifteen (15) feet from any open excavation. It is also important to
protect the stockpile with an impervious cover. We suggest the owner, and his
contractor, consider the use of a sandbagged or pegged-in-place overlapping visqueen
sheeting for this purpose. It is also advisable to construct either a shallow swale, a low
earthen berm or an erosion fence around the perimeter of the stockpile. In this manner,
it should be possible to capture any surface water runoff from the stockpile and to help
prevent it from flowing onto the site and potentially transferring fines from the stockpile
to the site.
Geotechnical Engineering Study Page 10
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
Overexcavation: It appears that, with the exception of the removal of the potentially
compressible organic soils and the surfical uncontrolled fills, it will be unlikely that any
significant overexcavation will be necessary on this project. We estimate that an average
depth of about two feet of overexcavation is likely to be required for foundation
installation, and about four to five feet for utility trenches. The latter depth will, however,
be dependant on the location of the primary utilities in the surrounding streets.
he excavated native soils are generally considered suitable for re-use as a structural fill
elsewhere on the project, providing they are free of all organics and debris and are not
on the wet side of optimum moisture. Thus, it is appropriate to stockpile these excavated
soils for later use.
In any excavation in excess of four feet in depth that is not shored. including utility
trenches, the excavation side slopes must be laid back at an appropriate gradient in
conformance with the current local and OSHA safety standards. This should be expected
to increase the amount of material that must be excavated, stockpiled and either re-
placed or re-used as backfili.
All overexcavated material not removed from the site and disposed should be stockpiled.
Stockpiled material should, where possible, be protected against the elements. As with
the topsoil, this can be accomplished by covering the stockpile(s) with a pegged or
sandbagged in-place overlapping visqueen sheeting. We recommend all stock-piles be
set back at least fifteen (15) feet from the crest of any slope or excavation. Only the re-
usable soils should be stockpiled. Any unsuitable soils should be removed from the site
and disposed in accordance with the appropriate local regulations. Here too, we
recommend the installation of either a shallow swale, a low earthen berm, or a silt fence
to prevent surface flow from the stockpile surface from reaching the excavated building
areas of the site, or transporting soil fines from the stockpile to the site.
Excavations and Slopes: As indicated above, site development appears likely to
involve only shallow excavation for removal of organic and fill materials, foundation
installation and for installation of utility lines. Although the potential extent of the
excavation work appears to be minimal in depth, both the owner and the earthwork
contractor should be aware that in no case should slope heights or excavation depths,
including utility trenches, exceed those specified in local, state and federal government
safety regulations, particularly the OSHA Health and Safety Standards for excavations,
29 CFR Part 1926, dated October 31, 1989.
We understand that these regulations are being strictly enforced and, if they are not
closely followed, both the owner and the earthwork contractor could be liable for
substantial fines. We also recommend that the owner's and contractor's attention be
Geotechnical Engineering Study Page 11
' 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
' directed to the following local and state regulations. WSDOT Section 2-09.3(3)B, and
Washington Industrial Safety and health Act, Chapter 49.17 RCW.
' Based on the soil conditions observed in the original study over the proposed building
areas of the site we believe that the in-place soils should be classified as Type C soils
in accordance with current OSHA regulations. Thus, excavations extending down to
depths of greater than four feet should be sloped back at a gradient of 1.5H:1V, or flatter.
' If slopes of these inclinations, or flatter, cannot be constructed, or if excavations of
greater than four feet in depth are required, temporary shoring may be necessary to help
protect against slope or excavation collapse. If temporary shoring is required, we will be
available to provide geotechnical shoring design criteria, if requested.
We strongly recommend that, if utility trench excavations are to extend to a greater depth
' than four feet, the utility contractor employ a steel trench box to help preserve the inte-
grity of the excavation. Failure to use a trench box could result in trench sloughing or
collapse and development of a significant threat to his workers health and safety.
tThe earthwork contractor should request that all excavations be observed by our
representative to verify that conditions are as anticipated. If warranted, supplementary
recommendations can then be developed to enhance stability. Such recommendations
should include, but not necessarily be limited to, flattening of slopes or installation of
surface or subsurface drains. I
' It is also critical that all exposed cut or fill slope faces be protected against erosion. This
can typically be managed by covering the exposed face with a sandbagged or pegged-in-
place impermeable plastic sheeting. In addition, we recommend that a shallow swale or
ditch be dug along the toe of any excavated slope to collect the surface water runoff.
' The collected water should be directed to a positive and permanent discharge, such as
a nearby storm drain.
' Proofrolling: Where appropriate, the existing ground surface where structural fill,
foundations, floor slabs or pavements are to be placed, should be proofrolled under our
' representative's observation. Depending on the time of construction, the proofrolling can
be accomplished with a vibratory steel wheel roller if the soil is dry. If moist, we
recommend the use of only the roller's dead weight. In wet weather, proofrolling should
' be discontinued to avoid the risk of pumping moisture up into the fill soil and, thereby,
creating an unacceptable condition that might require re-excavation and re-placement of
the partially compacted fill soil.
1
l.
Geotechnical Engineering Study Page 12
95-1550 Sound Mazda Sales and Service Facility
■J�II February 6, 1995
The purpose of the proofrolling is to determine the presence and define the approximate
areal extent of any soft or unstable areas. Soil in any soft or unstable areas should be
moisture conditioned, as appropriate, and re-compacted. If after re-compaction these
�J areas remain soft or unstable, they should be overexcavated and the unsuitable materials
removed and replaced with compacted structural fill, or a crushed rock, to a depth that
IL provides a stable base. Typically, a depth of two to three feet is adequate for this
purpose.
(:g
e-Densification: It is also critical that all load supporting areas of the prepared
rade be thoroughly re-densified before any construction takes place. We recommend re-densification be carried out with a vibratory steel wheel roller making a minimum four passes over the subgrade. One pass is considered to be a passage of theuipment forward and backwards over the same strip of subgrade.
Structural Fill: Structural fill is defined as any fill placed under buildings, roadways,
slabs, pavement, or any other load-bearing areas. Ideally, but particularly for wet weather
construction, structural fills should consist of a free-draining granular material with a
maximum size of three inches. The material should have 75% passing the number 4
mesh sieve and no more than 5 percent fines (silt and clay sized material passing the No.
200 mesh sieve). During dry weather any organic-free, compactible material meeting
the above maximum size criterion is acceptable for this purpose.
From our field observations, it is our professional opinion that the majority of the on-site
materials, including existing organic-free surficial fills, are generally suitable for re-use as
a structural fill under dry conditions. However, to use the in-situ soils it will be necessary
to first remove all organics and debris and, if necessary, to aerate the soils to make sure
that the in-situ moisture content is within three points of the materials optimum moisture
content.
Fill Placement and Compaction: Structural fill under floor slabs and footings, in utility
J trenches, or in roadway or parking lot subgrades should be placed in thin horizontal lifts
not exceeding ten (10) inches in loose thickness for heavy compactors and four inches
for hand held compaction equipment. Each lift should be compacted to a minimum of 95
percent of the maximum dry density, as determined by ASTM Test Method D-1557-91
(Modified Proctor), or to the applicable minimum City standard, whichever is the more
conservative. This is of particular importance in utility trenches located in any
pavement areas.
In roadways, we recommend that the upper two feet of any subgrade fill be compacted
to at least 95 percent of the maximum dry density, as determined by ASTM D-1557-91.
1
Geotechnical Engineering Study Page 13
' 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
To facilitate the earthwork and compaction process,the earthwork contractor should place
and compact fill materials at or near (typically within about two to three points) the �(
' optimum moisture content. If fill materials are on the wet side of optimum, they can be J
dried by periodic windrowing, spreading and re-spreading and aeration, or by intermixing
lime or cement powder to absorb excess moisture.
' Utility Trench Fill: Since the proposed development of this property involves new
building and roadway construction on a previously undeveloped piece of property it is
' virtually certain that new utility lines will need to be brought into the site. Before doing
so, any and all existing utilities should be located and identified to avoid potential risk of
damage during construction.
We recommend that the owner attempt to bring any new utility line into the site by the
' shortest possible route available. Phone and power may be available be means of
overhead pole supply. However, the majority of the utilities, such as water, gas, sewer,
cable T.V., and storm drainage will most likely be underground.
Cables are significantly less susceptible to settlement activity or distortion in installation.
Pipes can change shape because of inadequate support or excessive overhead loading.
' To avoid this possibility, we recommend that the contractor(s) make sure that each utility
line is set on a suitable bedding material in accordance with the specific pipe
manufacturers' recommendations. Once set in-place, it is critical that adequate fill
' support is provided beneath the pipe haunches to help prevent pipe distortion
under load, and that the fill cover within about one foot of the crown of the pipe be
adequately compacted with hand operated compaction equipment.
' In our experience utility trench fill has been the source of the majority of post construction
fill settlement problems, particularly in pavement areas. Many utility contractors expend
' little, if any, effort in placing trench backfill in thin layers, as described above, or in
compacting each layer of backfill to the recommended degree. As a result, over a
relatively short period trench backfills have a tendency to settle thereby leaving a hollow
' or depression along its alignment. _
We strongly recommend that all utility trench backfill be placed and compacted in the
' same manner as described for structural fill above. A typical depiction of the appropriate
degree of fill compaction is presented on Plate 3, attached. (Where recommendations
in this text differ from the plate, the text shall govern.) We also strongly recommend that
' the project specifications include the following specifics:
1 ] '
J
�1 Non-Roadway Floor Slab or
J Areas Roadway Areas
r� r
varies
� 2 feet
Backfili
80 `' varies
■J
r PIPE v�
Bedding `{ ti z;;+' Cf�"mot .e3':•�" rt�' tr2�;"y varies
1•Ni4:.>.fp} Y•:J'S1 ..p
l�•�C 1:).:.�.,.�Y{fa. 1'k
LEGEND
_ Asphalt/Concrete Pavement/Concrete Floor Slab
Base Material/Slab Base Rock
Backfill;compacted on-site soil or imported select fill material
Bedding material; material type depends on type of pipe and laying conditions.
Bedding should conform to the manufacturers recommendations for the type of
pipe selected.
® Minimum percentage of maximum laboratory dry density as determined byASTM
Test Method D 1557-78 (Modified Proctor)
� Creative Engineering options tw. TYPICAL UTILITY TRENCH FILL Plate
i „F,,,,, Sound Mazda
Geotechnical Engineering Study Page 14
' 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
' ■ All utility trench fill must be compacted to the degree specified
in the Fill Placement and Compaction section of this text, or as
' indicated on the project plans and specifications.
' ■ All utility trench backfill must be monitored and regularly tested
with either a nuclear density gauge or a sand cone device to verify
that the appropriate degree of in-situ compaction has been achieved
in the field.
' ■ All of the in-place density test data should be provided to the
geotechnical engineer of record for the project for his review
as quickly after its performance as is possible.
1
We also recommend that the owner insist on the performance of in-situ density
' testing of all trench backfills. As indicated above, this will allow for verification of the
degree of in-place fill compaction achieved in the field, and should point out areas where
problems might exist.
' Based on recent experience, we also recommend that, if not specifically directed by the
owner, all prudent utility trench contractors take it upon themselves to make sure that
' some form of backfill compaction verification (density testing) is performed during the
project. Failure to do so can result in problems with trench backfill settlement and, often,
' this leads to litigation. `
The owner might also consider including a section in the project specifications that
requires the utility contractor to make good all trench backfill settlement at his cost. This
should prove to be somewhat of an incentive to achieve a reasonable degree of trench
backfill compaction.
' When performing in-situ trench backfill density tests it is critical that the nuclear
testing gauge be calibrated in the trench. If the testing technician fails to calibrate
' the gauge in the trench the density readings obtained are likely to be worthless.
It is our current understanding that there are no existing utilities within the proposed
building area of the site; however, if utility pipes are encountered during construction, they
' should be plugged or removed so that they do not provide a conduit for water and cause
' soil saturation and stability problems.
Geotechnical Engineering Study Page 15
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
Fill Source Evaluation: If excavated site soils are to be used as a fill, or if any materials
are to be imported to the site for any reason, it will be necessary to evaluate the potential
fill source before any material is imported. We recommend that the geotechnical engineer
be required to visit each and every potential fill source to obtain randomly selected
representative samples of the potential source materials.
These samples will then be submitted for laboratory testing to determine the material's
maximum dry density and optimum moisture content. The source materials should be
.'� tested in general accordance with ASTM Test Method D-1557-91 (Modified Proctor). The
Maximum density and the optimum moisture content are then used in the field as a gauge
to determine the approximate degree of fill compaction being achieved by the earthwork
contractor. Depending on the general composition of the source materials, a gradational
analysis may be appropriate to determine both the gravel and fines content.
In-Situ Fill Density Testing: Based on our recent experience with construction projects
it is evident that there is a problem of potentially major concern occurring on many field
projects. This is the problem of matching the in-place density test results obtained with
a nuclear density gauge with the in-situ materials maximum dry density.
The source materials are tested in the laboratory to determine the materials' maximum
dry density and optimum moisture content and, where a change in the source material
appears to be occurring in the field, a second and/or third (or more) moisture/density tests
are performed. It is critical that all of the laboratory moisture/density curves resulting from
�1 these tests be plotted on the same sheet to create a "family" of curves. Then, each field
�J density test should be plotted against this family of curves to determine approximately
which of the curves is the most appropriate to the area being tested. From our
f� experience,this should result in a considerably higher percentage of the field density tests
achieving a satisfactory result. Failure to follow this process often leads to the use of an
incorrect moisture/density curve and, as a result, to a failing compaction test.
Foundations
F
ral: As indicated earlier, it is our professional opinion that the proposed building(s)
e supported on conventional spread footings. These footings should bear directly
her the thoroughly re-densified in-situ soils after removal of unsuitable organic soils
here appropriate, on a compacted structural fill pad. If thickened floor slabs are to
ed for interior foundations, these too must be founded at a depth of not less than
en (18) inches below site subgrade or the top of the floor slab.
Schematic Only- Not to Scale
�1 FOOTING
DETAIL
ood
�^0
Floor Slab
Soil
LEGEND
Compacted structural fill
Free-draining capillary break with minimum thickness of 6 inches
a Perforated or slotted, rigid plastic drain line laid with sufficient gradient to initiate gravity flow,
e4 with minimum diameter of 4 inches, bedded on and surrounded with free-draining granular
— drainage material per report tent
NOTES
_ • Minimum thickness of compacted structural fill, z - 18 inches
• Minimum lateral width of compacted structural fill beyond footing perimeters,z - 18 inches
• Minimum thickness of compacted structural fill beneath floor slab,d - 1 foot
• Excavated native subgrade to be thoroughly proofrolled and re-densdied in aocordance with recommendations in
attached text before any structural fill is placed
All structural fill to be compacted to at least 95 percent of the maximum ASTM Test Method D-1557-91 (Modified
Proctor)dry density
_Creative Engineering Options iw. Plate
STRUCTURAL FILL PAD DETAIL
Sound Mazda 4
l�nlfll F7d3�YI V1!CXOYILYKLS
at L
' Geotechnical Engineering Study Page 16
' 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
' If the structural fill option is selected we recommend that the fill pad beneath any
foundation be at least two feet thick. The pad should also extend horizontally for a I
' distance beyond each foundation perimeter equal to, or greater than, the thickness of the
fill beneath the footing. This tends to help in resisting the potential for lateral shear failure
in the near surface soils under load. It also creates sufficient open area for the contractor
' to use a larger piece of compaction equipment to re-densify the native subgrade soils.
A typical detail is provided on Plate 4, attached.
' Conventional Foundation Design Parameters: We recommend the following geotec-
hnical parameters be used in design and construction of conventional spread footings for
the proposed buildings:
1
■ Allowable soil bearing pressure for = 1,000 psi
' thoroughly re-densified in-place
soils with footing width of 1.33 feet
at a minimum depth of 1.5 feet
■ Allowable soil bearing pressure for = 1,500 psi
' thoroughly re-densified in-place
soils with a minimum footing width of
' 1.33 feet at a minimum depth of 2.0 feet
■ Allowable soil bearing pressure for = 2,000 psi
' thoroughly re-densified in-place i
soils with a minimum footing width of i
1.33 feet at a minimum depth of 2.5 feet
' or for controlled compacted structural = 2,500 psi
fill over re-densified in-place subgrade
' soils
' ■ Minimum recommended burial depth of perimeter = 2.5 feet
footings below lowest final design exterior
grade (assuming footings are supported on the
' in-situ site soils) Ir
1
'1 Schematic Only - Not to Scale
Building Load
J
� Jr
yv e v . I
Jt Option 1 -
J t Excavation and backf ill
Compacted granular
structural till
f�
Firm Native Soil
�l
Building Load
iJ 1
b
C
E
Compacted
Option 2 - structural fill
Transfer load to competent '
native soil
Firm Native Soil
Creative Engineering Options w Plate
. FOUNDATION SUPPORT DETAIL �
n Fmrr��he<ceo,�r„az Sound Mazda
a
' Geotechnical Engineering Study Page 17 NT
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
' ■ Minimum recommended burial depth of perimeter = 18 inches
' footings below lowest final design exterior
grade (assuming footings are supported on at
least two feet of compacted structural fill)
' ■ Minimum recommended depth of burial of interior = 2.5 feet
' footings top of floor slab (assuming support is
by in-situ site soil)
' ■ Minimum recommended depth of burial of interior = 18 inches
footings top of floor slab (assuming support is
' by at least two feet of compacted structural fill)
■ Minimum recommended width of perimeter footings = 16 inches
' ■ Minimum recommended lateral dimension of column = 36 inches
footings
tA one-third increase in the above allowable soil bearing pressure may be used when
considering short term transitory wind and seismic loads.
' We recommend that wherever a continuous footing crosses a cut to fill transition tension
reinforcing steel be added to the tops of the foundations. The structural engineer should
' evaluate the appropriate size and locations of all tension reinforcing steel. From our
experience we recommend that such additional tension steel extend for a distance of
' about ten (10) feet beyond the perimeters of the transition.
Should portions of any column foundations be located in a cut-to-fill transition area, the
' foundation should either be extended down to bear on the underlying competent or
thoroughly re-densified native soil, or it should be supported on at least two feet of
compacted structural fill (see Plate 5).
' Settlement: On the basis of the observed site soil conditions and our engineering
analyses, and working on the assumption that the foundations will bear on thoroughly re-
' densified soils, it is our opinion that the maximum settlement potential under the proposed
combined building dead and live loads is likely to be within the building's tolerable limits.
Geotechnical Engineering Study Page 18
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
Providing the recommended site treatment is performed, we estimate that the maximum
potential settlement is likely to be of the following order:
■ Total estimated post-construction = 1-1/2 inches
settlement
■ Total estimated differential settlement = 1/2 inch,
over a distance of 40 feet or less
_y The owner should understand that the majority of these magnitudes of total and
differential settlement should be expected to occur as the dead loads are applied during
the construction of the building. The remainder should be expected to occur after
construction is completed.
Lateral Load Resistance: Lateral loads can be resisted by a combination of passive
pressures acting on the buried portions of the building and foundations, or friction
between the concrete elements of the foundation and floor slab and the underlying
subgrade. For the former, the concrete must be placed neat against competent native
soil or compacted structural fill. We recommend the following parameters be used in
design.
■ Passive pressure equivalent fluid = 280 pcf
weight provided by re-densified
in-place site soils
■ Passive pressure equivalent fluid = 360 pcf
weight provided by compacted
structural fill
■ Coefficient of friction applicable = 0.30
to re-densified in-place soils
■ Coefficient of friction applicable = 0.38
"� to compacted structural fill
t ILGeotechnical Engineering Study Page 19
' 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
' We also recommend the upper one foot of passive pressure be neglected in design
unless the soil is overlain with either a floor slab or paving.
' Buried or Basement and Retaining Walls
Although the current conceptual plans do not appear to include either daylight basement
or retaining walls, it is possible that there may be a buried mechanic's pit or other local
' below grade structure. We have, therefore, provided appropriate wall design parameters
for your use should they be included later. Any buried or retaining wall must be capable
' of restraining the lateral soil and surcharge loads imposed upon it. We recommend that
the following parameters be used in wall design:
' ■ Active equivalent fluid weight for = 45 pcf
walls that are free to rotate at
' least 0.001 times the wall height
' ■ Active equivalent fluid weight for = 65 pcf
walls that are fixed against rot-
ation
' All basement or retaining walls should be provided with a suitable drainage control system
' to prevent the potential for hydrostatic pressure buildup. This drainage system is
discussed in more detail in the site drainage section of this report. It is also crucial that
any additional surcharge loads, such as traffic or stacked materials, be included in wall
' design. Any such surcharges should be added to the above loads for design.
' Slab-on-Grade Floor
A concrete slab-on-grade floor is appr end
' that it be supported on at least tw ve (12) inches of compacted structural fill, o a
thoroughly re-densified native subgra oval of an and ' g
potentially compressible organic soil. Any disturbed soils should a carefully re-
' compacted before constructing the slab. We recommend that the following parameter be
used in floor slab design: IF
1
1
J
Geotechnical Engineering Study Page 20
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
-,� ■ Modulus of vertical subgrade reaction = 70 pci
for re-densified in-place soil
■ Modulus of vertical subgrade reaction = 175 pci
' supported on compacted structural fill
Because of the potential for underslab seepage give recommend a capillary break be
included beneath the slab for por transmission. This capillary break
should consist of at lea four inches of clean, ee-draining granular material, such as
sand or pea gravel. This is pictorially epi ed on Plate 6, attached.
In areas where moisture vapor transmission through the slab is undesirable, we
recomme rmeand an in or barrier be installed over the capillary break beneath
■J1 the slab. 6 mil plastic me bran s typically adequate for this purpose. This
membrane wi e p preven moisture vapor transmission up through the slab and the
�y associated moisture-related damage to interior furnishings and salt generation in the
Jsurface of concrete slabs.
It is very important that all building utilities are installed before the capillary break and
visqueen barrier are installed to avoid damaging them. Damage to either element could
' result in a non-functioning system and that could lead to creation of the problems this
system is designed to avoid.
As an additional protective measure, the owner may also wish to consider placing two to
four inches of damp sand over the membrane. This will help protect the membrane
during construction and will help in curing of the concrete slab. It will also help to prevent
r� cement paste bleeding down into the underlying capillary break through joints or tears in
the visqueen barrier.
Seismic Risk
While we did not perform a detailed seismic risk analysis for this project, it is clear that
earthquake ground motion response is a particularly important factor and that it should
be carefully considered in structural design. Historically, the Puget Sound Region has
been subjected to frequent earthquakes of moderate intensity, and is designated in the
Uniform Building Code as Seismic Zone 3. Thus, for structural stiffness design we
recommend the following Seismic Zone factor be used:
f
�1 Geotechnical Engineering Study Page 21
' 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
■ Seismic zone factor, Z = 0.30
Two earthquakes that resulted in significant damage occurred in 1949 near Olympia, and
in 1965 near Seattle. The April 3, 1949 earthquake is the largest recorded earthquake
in the region, reaching a magnitude of 7.1 . It was felt over 150,000 square miles,
resulting in $25 million in damages, eight (8) deaths and many injuries. The April 29,
1965 earthquake of magnitude 6.5 was felt over 130,000 square miles, and resulted in
widespread damage in the Seattle area.
�•� Approximate acceleration levels are only estimatable at this time for the state of practice
i� due to complexities of the area that could include focusing and other complex concepts.
However, as a relatively conservative design approach, we suggest that a Richter
magnitude 6.8 earthquake be used as the design event, and assume a recurrence interval
■y of seventy-five (75) years for the reasonable building lifetime. From this magnitude, the
■-J� calculated probable Mercalli intensity for an earthquake centered directly beneath the site
(an unlikely event) is 7.5. On this basis, and using the values typically employed in the
City of Seattle for alluvial/fill soils, we estimate the lateral acceleration for use in design
■�' should be on the order of the following:
■ Lateral acceleration = 0.20g
The above seismic parameters should be used in design, but one should remember that
they are based on some conservative assumptions.
Liquefaction
The in-place site soils are generally described as being medium dense in nature and
appear to increase in density with depth. They also appear to consist predominantly of
fine to coarse, granular, non-plastic soils. It is also apparent that the local groundwater
level is well below the site grade and is unlikely to be capable of "surging" and saturating
the soils during an earthquake.
..� Because of this combination of conditions, and assuming that the recommended re-
densification of in-place soils is adequately performed, it is our professional opinion that
the risk of the in-place soils being subject to liquefaction under severe earthquake
conditions should be considered low. As indicated, the risk can be further mitigated by
1
Geotechnical Engineering Study Page 22
' 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
careful and controlled site re-densification, and the installation of appropriate site drainage
control measures.
' 1
Site Drainaae
' General: Because no well established groundwater level, and only evidence of light
groundwater seepage was observed at the time of our field study,we believe groundwater
' is unlikely to have a significant detrimental impact on either the earthwork operations or
construction. Nevertheless, we believe it will be prudent to install both short and long-
term drainage control measures as part of project design and construction.
1 Short Term Drainage Measures: Over the short term, we recommend that the earth-
work contractor be prepared to install several shallow sump pits to collect water in utility
trench or foundation excavations. All collected water should be pumped to a positive and
permanent discharge. (A positive and permanent discharge might consist of a nearby
storm drain catch basin, or similar facility.)
' Although the in-place soils are generally granular in nature,they are relatively fine grained
and are likely to be somewhat moisture sensitive. With this in mind, we believe it will be
' prudent to perform earthwork operations at this site, particularly utility trench and
foundation excavation work, during the drier summer months. In this area this is typically
' during the months of late June through October. I
The owner should also consider construction of either a low earthen berm or a shallow
' swale around the upgrade perimeters of all proposed building area excavations in an
attempt to intercept and collect any surface water flow. It is essential that all surface
runoff be directed away from the crest line of all sloping excavations and/or excavated
' subgrades, and not be allowed to sheet flow over the exposed surfaces.
Water should not be allowed to stand in any area where a building, floor slab, or
pavement is to be constructed. During construction, the earthwork contractor should
roller seal all loose surfaces at night or at the beginning of a weekend to reduce the
potential for moisture infiltration into the subgrade soils.
' Site grades should allow for drainage away from building foundations. We suggest that M 3
the ground be sloped at a gradient of three percent for a distance of at least ten (10) feet
' away from a building, except in areas that are to be paved.
Any excavation or slope areas, including utility trench excavations, should be protected
' against the elements during construction. This can be accomplished by overlaying the
r
Geotechnical Engineering Study Page 23
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
exposed slope surface with a sandbagged or pegged-in-place visqueen barrier.
Temporary site grading should be performed to create site grades that direct water away
from the excavation. We also recommend that the contractor consider installing either
a shallow swale or ditch along the toe of any protected slope to collect any surface water
runoff and to direct it to a positive and permanent discharge.
Long Term Drainage Measures: In the long term, perhaps the most critical element of
drainage control is to install drains along all building perimeter footings. These drains
should consist of a rigid, perforated or slotted, plastic pipe bedded on and sur-
rounded by a free-draining granular material. All drains should be installed at or
below the footing invert elevation and should be provided with sufficient gradient
' to initiate gravity flow to a positive and permanent discharge such as a storm drain
- catch basin. A typical detail is provided on Plate 6, attached.
' We suggest, if necessary, appropriate subsurface drainline locations be established
during the earthwork phase of the project by our representative when seepage areas and
conditions may be more clearly defined.
Any basement, below grade, or retaining wall should be provided with a drainage control
system: As with the foundation drains it should include a rigid, perforated or slotted,
■ _ plastic pipe bedded on and surrounded by a free-draining granular material. All drains
should be installed at or below the wall footing invert elevation and should be provided
with sufficient gradient to initiate gravity flow to a positive and permanent discharge.
We recommend that the free-draining material meet the requirements of the WSDOT
Standard Specifications for Road, Bridge, and Municipal Construction, Section 9-03.12(4)
Gravel Backfill for Drains, as follows.
Material and Percentage of
Sieve Size Material Passing
1 inch 100
3/4 inch 80 - 100
3/8 inch 10 - 40
#4 mesh 0 - 4
�l #200 mesh <2
J
Schematic Only- Not to Scale
' Slope t� o Drain
S / Exterior Wall
IT
y
ao°oo-ogo°p°Qao
Impermeable Visqueen
"° °" II oo°p%• VaporBarrier
D o:.nnL bit m9:,atci: 1
:. 1a.o�:.p;QobgQ.n.
p D,o4a p°C
c P Q�°onQ� Floor Slab
RT
--
.Od�rr° oap'
9 _ t
LEGEND
' ® Surface seal of native soil or other low permeability material. (Can be separated from underlying
free-draining material by building paper,visqueen or geotextile, at owners discretion
Free-draining,granular backfill material meeting the gradation specification presented below. r
6-inch minimum diameter, perforated or slotted rigid concrete, metal,or plastic pipe with tight jgints, with
a positive gradient sufficient to generate gravity flow and provided with accessible cleanouts at regular
n intervals. Perforations(3/16 to 1/4 inch diameter)to be in lower half of pipe, with lower quarter segment
' - unperforated to facilitate water flow. Slotted pipe to have 1/8-inch maximum width slots. Must NOT be
tied to roof downspout or perimeter footing dram lines.
Alternative composite geotextile drainage fabric attached to wall after the wall has been damp-proofed.
Capillary break placed beneath floor slab consisting of clean pea-gravel, 1/2-inch minimum washed 1
' rock,or clean sand,with a minimum thickness,t,o 4 inches.Capillary break to be separated from floor
slab by impermeable plastic membrane.
____= Approximate location of hydraulic connection between capillary layer and exterior wall or footing drain.
NOTES
• Minimum depth of footing burial, D - 18 inches.
• Estimated thickness of impermeable surface layer, S, -6 to 12 inches
• Minimum recommended thickness of capilary layer,t -4 inches.
' • Capillary drainage material beneath floor slab should be hydraulically connected to Perimeter subdrain pipe. (Use of
2-inch minimum diameter weep holes, as shown above, is one option of achieving this end.)
• Any backfill within 18-inches of wall should be compacted with hand-operated compaction equipment only. Heavy
' compaction equipment should not be used within 5 feet of wall to help avoid imposition of additional lateral bad on
that wall which could cause wall damage.
• All wall backfill should be placed and compacted in accordance with the recommendations contained in the Fill
Placement and Compaction section of the attached CEO, Inc.,report.
' • Wall drainage and backfill material should meet the following gradation requirements, (WSDOT Standard
Specifications for Road, Bridge,and Municipal Construction, action 9-03.12(4)Gravel Bac kfill for Drains), unless
otherwise recommended by the geotechnical engineer:
' Material and Percentage of
Sieve Size Material Passing
1 inch 100
314 inch 80- 100
' 3/8 inch 10-40
$ #4 0-4
m #200 <2
' Creative Engineering Options . WALL AND FOOTING DRAIN DETAIL Plate I
�Lvnrkrn vra¢tY�g t,me ceo}ckvices Sound Mazda 6
8
Geotechnical Engineering Study Page 24
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
All areas to receive these drainlines should be observed by the geotechnical engineer.
Where the immigration of fines from the native soil into the above-referenced drainage
' material may compromise the drain,the gravel backfill should be protected by a geotextile
filter cloth. This form of drain is also pictorially depicted on Plate 6.
' As an alternative to a free-draining backfill, the owner may wish to consider the use of
a composite drainage fabric, such as Miradrain or an approved equivalent. This
composite should be placed directly against the face of the wall (after the wall has been
' suitably waterproofed) with the filter cloth facing the soil surface. The composite should
be wrapped around the basal drain line to make a clean and direct connection. Backfill
is then placed against the geocomposite covered wall and is compacted as it is raised
back to design site elevation. A typical pictorial depiction of these drainage system
elements is also provided on Plate 6.
' Roof Drainage: Under no circumstances should the building roof downspout lines be
connected to the footing drains. Downspouts must be separately tightlined to discharge.
We also recommend the installation of sufficient cleanouts to allow for easy and periodic
downspout drainline flushing and maintenance. It has been our experience that the most
functional cleanout spacing if for one to be installed at any bend in a drain system and
at a spacing of about thirty-five (35) feet in straight pipe runs. This should be expected
to help keep the potential extent of drain line clogging to a small segment of pipe that can
1 be cleared with relative ease.
Erosion Hazard: We assume that the recommendations presented in this report for
performance of site earthwork operations are to be closely followed during construction,
and that the erosion control measures, described below, will be implemented. Based on
the existing site conditions and the above assumptions, it is our professional opinion that
the this site does not present an erosion hazard.
Erosion Control: We recommend, as a minimum temporary measure, that the earthwork
contractor erect a sift fence along the downgrade perimeter of the site. Similar fences
should also be erected upgrade of any excavation, and should be set sufficiently far from
the edge of the excavation to allow for free passage for the workmen. They should,
however, be upgrade of any drainage control swale or berm.
T The silt fence should consist of a geotextile fabric produced for this purpose and suitable
_ J for erosion control, such as a Mirafi Envirofence or an approved equivalent. It should be
supported on "Hog Wire" attached to steel or wooden stakes driven into the ground at
relatively close center to center spacings. Approximately the bottom eight inches of the
geotextile should be buried into the site subgrade to help avoid the risk of sediment laden
1�
--...;= �'_..c� ...r.L^oi..�.�4;9o:PY.4'�:4-.•- .... .. _�._-.Y. ...-'F-...eS?�.TGY�K':_ .;
' Schernatic Only- Not to Scale
Newry ggrailed or
' \ distured site surface
V, Geotextile filler fabric material
' 604ich wide rolls,use rings to
attach to wire fabric
2'x 2•xid 6'
galvanized
WWF Supporting
' I post 2.S
Tr
' � rc
a
Geotextile Staples or wire 2'x 2'x 14 gauge galvanized
' filter fabric rings or
welded wire fabnc or equivalent
' \In
II II
II V II II
II II II
n I Existing I I " I i U I I rs
' grade Ir II II
II V II U II
11 II II
.ti \— \— t
1 IVI I I I—I \ IVI 1
2•x 4•Douglas Fr at 6•-0•O.C. 6•-0•cc \Bury bottom of geotextile erosion
No.1 grade or better,or steal pest maximum fence material in 8•x 6'trench
' NOTES
• The filter fabric should be purchased in a continuous roll cut to the length of the barrier to avoid use of joints.When joints are
' necessary,filter cloth should be spliced together only at a support post,with a minimum six-inch overlap,and both ends securely
fastened to the post .
• The filter fabric fence should be installed to follow the contours(where feasible).The fence posts should be spaced a maximum of
six feet apart and driven securely into the ground(minimum,of 30 inches).
' A trench should be excavated,roughly eight inches wide and twelve inches deep,upslope and adjacent to the wood post to allow
the filter fabric to be buried.
• When standard strength filter fabric is used,a wire mesh support fence should be fastened securely to the upslope side of the posts
t using heavy-duty wire staples at least one inch long,tie wires,or hog rings;The wire should extend into the trench a minimum of
four Inches and should not extend more than thirty-six inches above the original ground surface.
• The standard strength filter fabric should be stapled or wired to the fence,and twenty inches of the fabric should be extended into
the trench.The fabric should not extend more than thirty-six inches above the original ground surface. Filter fabric should not be
' stapled to existing trees.
• When extra-strength filter fabric and closer post spacing are used,the wire mesh support fence may be eliminated.In such a case,
the filter fabric is stapled or wired directly to the posts.
' : The trench should be badcfilled with 314 inch minimum diameter washed gravel.
Filter fabric fences should be removed when they have served their useful purpose, but not before the upslope area has been
permanently stabilized.
' • Filter fabric fences should be inspected immediately after each rainfall and at least daily during prolonged rainfall.Any required
S repairs should be made immediately by the contractor.
'r^Creative Engineering Options iNc. TYPICAL FILTER FENCE DETAIL Plate
A FM Raaltlng in r•e 4rosc� Sound Mazda 7
y
Geotechnical Engineering Study Page 25
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
water flowing out beneath the fence. A typical pictorial depiction of this filter fence is
presented on Plate 7, attached.
Overthe long term we recommend that all graded or exposed soil surfaces that exist after
construction be protected against the elements. This can be accomplished either by
careful landscaping or by re-vegetating the exposed areas with a seed and mulch cover.
This latter option is often referred to as "hydroseeding" and places a layer of seed and
mulch directly onto the exposed soil surface. Ultimately, the seed germinates and the
' root mat and vegetation, usually grass, take hold and "knits" the soil surface together
T1 thereby helping to prevent erosion. Depending on the time that the hydroseeding occurs
J it may also be helpful to use a pegged or sandbagged-in-place erosion control blanket to
help keep the seed and mulch in-place until such time as the seed can germinate and the
root mat take hold. Jute matting, North American Green erosion blankets, or "Excelsior"
matting are appropriate for this task.
Pavement Areas
y1, General: There are two important elements that need to be addressed in site access
roadway and parking lot construction, the subgrade and the design pavement section.
The following paragraphs provide information regarding the geotechnical aspects of both
these elements.
Subgrades: The performance of all site roadway and parking lot pavements is strictly
related to the condition of the underlying subgrade. If this is inadequate, no matter what
pavement section is constructed, settlement or movement of the subgrade will be
reflected through the paving. In order to reduce this risk, we recommend the pavement
subgrades be treated and prepared as described in the Site Preparation section of this
report.
This means all subgrades should be thoroughly proofrolled and re-densified. The native
soil subgrade should be thoroughly re-compacted and densified. At least the top two feet
of any subgrade fill should be compacted to 95 percent of the maximum dry density (per
ASTM D-1557-91, see Plate 3).
It is possible that some localized, and perhaps extensive, areas of soft, wet or unstable
- subgrade may still exist after this process. If so, overexcavation of the unsuitable
materials and their replacement with a compacted structural fill, crushed rock, or quarry
.■JI spalls may prove appropriate. Typically, overexcavation and removal of between about
one and two feet of material is adequate for this purpose.
Geotechnical Engineering Study Page 26
1 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
Depending on the nature bgrade at the time of construction, it may also
eotextile to be appropriate to use a arate fresh and competent pavement base
1 materials from the underlying subgrade soils and to help strengthen the pavement
section. We recommend that contingencies be provided in both the construction budget
and schedule to accommodate this potential need.
I1 In the event that a geotextile is needed for use in separating the structural fill from the
--J roadway alignment subgrade, we recommend that a Mirafi 500X, or an approved
1 equivalent, be used. To achieve the benefits and maximize the geotextile's capabilities,
l it is also critical that the selected geotextile be installed in strict accordance with the
J manufacturer's specifications and guidelines. If there should be a conflict between the
manufacturer's specifications and the recommendations in this report, the specifications
should govern.
1� The contractor should pay particular attention to the compaction of utility trench backfill
wherever a utility trench is located in, or across, a pavement area. It has been our
experience that poorly or inadequately backfilled utility trenches are the primary cause of
pavement damage. The appropriate backfilling methodology, including monitoring and
testing, is described earlier in this report under the heading of "Utility Trench Fill".
1� Pavement Sections: Although we understand that the site pavements are likely to be
minimum City of Renton standard sections, we have provided two alternative
1 recommendations for pavement sections for the lightly trafficked access and parking
— areas and for the heavier trafficked areas. In the lightly-loaded areas, which must be
clearly defined on the project plans by your civil engineer, we recommend the following
1 minimum design pavement section suitable for use over a suitably prepared subgrade:
■ Two inches of Class B Asphalt Concrete surfacing (AC)
over four inches of Crushed Rock Base (CRB) material,
or
— ■ Two inches of Class B AC over three inches of Asphalt
�1 Treated Base (ATB) material.
Heavier truck-traffic areas will require thicker sections depending upon site usage,
pavement life and site traffic. For this project we have made some assumptions
regarding these elements. Firstly, we assumed that the daily traffic would consist of one
�+ thousand five hundred (1,500) vehicles, a highly conservative estimate in our opinion.
Geotechnical Engineering Study Page 27
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
We also assumed that the traffic would be confined to two lanes, one in each direction,
and that the truck traffic would be split at 50 percent in each direction. We also assumed
that the subgrade soils were sufficiently competent to provide a CBR value of 5 for design
purposes, a relatively low value for the described soil type and recommended re-
densification treatment.
By treating the paved areas as an "City Street (local)" (Asphalt Institute nomenclature)
we estimated that the truck traffic would make up about 5 percent, or less, of the total
daily vehicular traffic. We also assumed that the pavement lifetime would be twenty (20)
years. Using these assumptions, and taking the maximum axle load as eighteen
thousand (18,000) pounds, we used the Asphalt Institute method for design of the heavier
truck traffic area pavement. Based on our analysis, we recommend the following
minimum pavement sections:
■ Three inches of Class B AC over five inches of CRB,
or
■ Three inches of Class B AC over four inches of ATB.
�l
' If requested, we will be pleased to help develop appropriate, and more specific, pavement
sections for heavy traffic zones once the specific design criteria are known.
Roadway Base Materials: In our opinion, based on the nature of the re-compacted and
densified in-place subgrade soils, either base material is acceptable. However, if
construction is to be conducted in the wetter winter months (typically October through
May) the owner should consider using the ATB option. This will not only provide a
competent "blacktop" surface that will help protect the site from construction activity, but
will also provide a clean, dry and competent surface on which to store and protect
construction materials. It has also been our experience that in spite of its slightly higher
— initial cost, this form of surfacing requires considerably less maintenance either during or
after a winter construction period.
4] If there is a need to use a geotextile mat over the subgrade, the owner will also need to
provide a thin protective layer of sand overthe geotextile to avoid the potential for burning
4] the fabric when the ATB is placed. ATB is usually placed at a relatively high temperature.
While the use of CRB offers little advantage over the ATB from the structural viewpoint,
it is significantly more susceptible to deterioration and expensive maintenance during
Geotechnical Engineering Study Page 28
95-1550 Sound Mazda Sales and Service Facility g
' February 6, 1995
winter use. In numerous instances the replacement of the CRB has been necessary
before paving could be accomplished because construction traffic forced the CRB down
into the underlying subgrade. Although the use of a geotextile can help prevent such
separation and contamination of the CRB, it must be paved over before the building can
be opened for occupation.
With the ATB, it is possible to stripe and mark the material and to use it as the
"pavement" so the building can be used. If desired, the ATB can be left undisturbed in-
place for one or more seasons until the great majority of any settlement-related
1� movement has an opportunity to occur. Then, any necessary maintenance can be
performed and the final AC surfacing installed. This should avoid the need for any
significant future pavement surfacing maintenance.
1�
1�
1]
V
U
rV
Geotechnical Engineering Study Page 29
95-1550 Sound Mazda Sales and Service Facility
l February 6, 1995
CLOSURE
1 Limitations
J The above information is being provided solely as a service to our client. Under no
1 circumstances should the above information be interpreted to mean that Creative
J Engineering Options, Inc., is assuming any responsibility for construction site safety,
measurements or dimensions, or the contractors or subcontractors activities. Such a
] responsibility is not being implied and should not be inferred.
Our recommendations and conclusions are based on our review of the site materials
observed, our geotechnical engineering analyses, the design information provided, and
our experience and engineerng judgement. The conclusions and recommendations are
J professional opinions derived in a manner consistent with that level of care, skill and
competence ordinarily exercised by other members of the profession in good standing
currently practicing under similar conditions in this area only. No other warranty,
Jexpressed or implied, is made.
The recommendations submitted in this report are based upon the data obtained from the
exploratory test pits and our site observations. These data pertain to the times and
locations where they were obtained only, but are assumed to be reasonably represen-
tative of the conditions beneath the majority of the area explored. Soil and groundwater
conditions between test pits may vary from those encountered. The nature and extent
of variations between the exploratory locations may not become evident until construction.
If variations do appear, the geotechnical engineer should be requested to re-evaluate the
recommendations of this report and to modify or verify them in writing prior to proceeding
with the construction.
l Additional Services
Plan and Specification Review: We recommend that CEO, Inc. be retained to perform
a general review of the final design plans and specifications. This will allow us to verify
that the earthwork and foundation recommendations have been properly interpreted and
implemented in the design plans and in the construction specifications.
Pre-Construction Meeting: Given that some selective overexcavation and site treatment
' is required, and because of the potential concerns related to sign demolition and removal
and site earthwork operations, we strongly recommend that a pre-construction meeting
be held on-site. The meeting should be attended by the owner (or his representative),
L
tGeotechnical Engineering Study Page 30
95-1550 Sound Mazda Sales and Service Facility 57
' February 6, 1995 N7
' the architect and the civil and structural engineer, the contractor, the geotechnical
engineer, and any of the appropriate City staff.
' By discussing the proposed construction sequence and outlining potential problems at this
meeting it should be possible to make sure that the contractor is aware of all the potential
' difficulties he might encounter during construction. In this manner it is also possible to
avoid a significant number of construction extras and to help provide a smooth running
project. This meeting also provides an opportunity to verify that the selected contractor
' has been provided with, and has read and understood the recommendations contained
in, the project geotechnical report. M
' Construction Monitoring and Testing: For continuity, we also recommend that CEO
be retained to provide geotechnical services during construction. This is to observe
compliance with the design concepts, specifications or recommendations and to allow
' design changes in the event subsurface conditions differ from those anticipated prior to
the start of construction. IL
This service would allow us to make an appropriate determination regarding the use of
' either structural fill on re-densified native subgrade soils for foundation support. It also
allows us, on the owners behalf, to verify allowable soil bearing pressures in foundation
subgrades and that any structural ortrench backfill materials have been compacted to the
' degree required, and that the proofrolled pavement area subgrades are competent. IF
' We do not accept any responsibility for the performance of the foundation or earthwork
or any other geotechnical aspect of the project unless we are retained to review the
construction drawings and specifications, and to provide construction observation and
' testing services.
' V_
1 ir
W
.. .-.. -- - -. '• - r:...s ir:�ra'rxx'si.i.Yr�i.G XVTv-.::< _.�...
�J
-'J
�J
APPENDIX A
94-1550
FIELD EXPLORATION PROGRAM
1 Geotechnical Engineering Study Page 32 IL
' 95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
APPENDIX A
' Field Exploration Program
94-1550
1
Our field exploration was performed on December 28, 1994. The subsurface conditions
' were explored by excavating a total of nine exploratory test pits to a maximum depth of
about eleven (11) feet below the existing surface at the approximate locations shown on
' Plate 2, Site Plan.
The approximate test pit locations were determined by pacing from, and the elevations
' were approximately determined by eye with respect to, a temporary benchmark, the top I
of the southeastern bolt of the light standard in the northeast corner of the property at an
assumed elevation of 100 feet. The locations and elevations of the test pits should
' be considered accurate only to the degree implied by the methods used.
The field exploration was continuously monitored by an engineering geologist from our
' firm who maintained a log of each test pit. Our representative classified the soil
encountered in the pits, obtained representative soil samples and observed pertinent site
features. Soils were classified visually in the field in general accordance with the Unified I
' Soil Classification System (USCS) which is summarized on Plate 8, Legend.
Individual logs of the test pit excavations are presented on Plates 9 through 13. The final
' logs represent our interpretation of the field logs and review of the acquired representative
soil samples. The stratification lines on the logs represent the approximate boundary
between soil types. In actuality, the transition may be more gradual or more severe.
' Representative soil samples were placed in closed containers and returned to our
Redmond office for further examination and review.
t
Unfiled Soil Classification System Component Definitions by Gradation
.mot SCYLCUSSFKA)ION-GFNE w COMR]RaTn SZE VMIGE
J1 GRM P DESC9PIIONS
Gr^0 GV/ Vid Gratlee Gr .Grael-Sob
/n 0 M6paa.lAk«NO Fna Boutlai M Qn
Gm" Oran Grame
� look«rb a.al GP J-� POayGracelGmer,Gred CnOt2es 3n.m 12 n
COX SaM Mu¢ures.IAOe«No Frcs
cab More mat Sty Gcaca.Gr -Sara- Grans 3n mNo.4l4.]6mm)
r>pty Chase Graew•met GM St Mwu 5 Came game 3.b 314 n
Fraction FutslappCade Co y Fne gaze 3/4b wW 41476mm1
_' Reoinerlm anwn d uMal GC Gay-Momaetr •G2M-Sab-
w 4Sae
sand No.414]6nm)m No.2001o0]4mml
lGlr-Gr $drAm,Grlwdy Coax sad No.414.]6mm1 m Na,10(2.IXart
SW SanOS lAre«No Fna raeaaa tam No.10120rranl mNo.4010.42mm)
Ntl Ckan SarlO :::
Saroy Ilek«no feral r1:1j W«Y-Gr WSame Graff
Fne tatl ab.401042mmlb No.20010.0]nrnf
-'� Sot fyfyJ Soros lime«NO Fna
Mde elm Si aW Cla/ Sr�mn 0.2W 100)mm)
'sits,-'$°I
50%MaeM M«eeai ! ya Sty SaiOt.Satl-SaMmin
Ngermal 501E Ccdrse SatlsvM :%3:iF;h
'
S 200 Sae p urg FnalaPpeaae S°e S-eew�n rna amwrxdma) x °afeyvna'Sar°-°arMmm Descriptive Terminology Denoting
wKwganx terymUn-/9� Component Proportions
MR. Fne av Ste w/S
FM Site trvganc Gays d Law b Meelum MUM. OESON' F MRMS P/J!C><DF iRCFORIION
'� GrarkO old L9ud lint CL Gc vOry+.s'M'Q�--Hr 0"a lt9n
Sob Oats dates w Trace 0.5%
0r9aa S av agmc 1@ 5-12%
P� SLY Oats d law Munir Sme«A-Ijerae la) 12-30%
"d M-50%
Iror�rx SRI>.Mio[ews«Omn�'alw FM
Wd«Sly Sob
ala Lqud tin 04 aaxr Fa t1afi Samples
50% Ory+ Great ebn 50
Smaller Cwn _- Orja Drysd Me]um b Hig1
' r'%200 Sine OH n Cy,CRgar Sao P Samprr nNled
SS
R ss c
FKjy Gga �` wg Bantle 12 �a ro HayDurypSp
m
I v4 sneoy T"
l,' Topoll s; Hunan aro Duff later Ply Pxdrer Sargkr
a auR
C Co el
Fr HigiV�Cnrerw+erio
D1af game ale user,m.acne b«delne sot nadcamn.Upp& Iems Vn designee Marge C"ffi e VPon
Iapor�y�'9 tnte+[ae Ime erred,Cai9^are ctaturc�no[tambl by eboramxY rangRelative .
I
i Density Utiliz ng StandardPenetration Test Values
Notes
V WATER LEVEL(DATE)
COHESCMESS S0641 COIIESNE SDa5lb1
11 WATER OBSERVATION WELL
DvsiPy(c) N.OlowirR(cl Dmvty Cmsismcy N CbwvRlcl Shea Saengdidl
154 IPA qc TORVANE READING,tsf
I IOpY o m 1 0 - 5 Vey soft G m 2 <2-
1 4 m 10 Is - 35 Sac 2 m 4 ma - 100 qu PENETROMETER READING,Lsf
Compact 10 m 30 35 - 65 Fum 4 m h 500 - 1000
Dense 30 m 50 65 - 95 Us 6 m IS IWO - 2000
very oche oerso >es veryar IS m 3o moo - 4" W MOISTURE,peroentofdrywoght
Hare aer 30 >4000
(a)Sda cmssvg ap rod.saro,aro vt Bern sgata¢y«n c«ra+aim.possewrg no cnarxarebn a platbcry.arm pef DRY DENSITY,pounds per cubic it
erri gdw4dbe0anor.
lbl sow pmwmwg ee cnaactermkt of 0. W,ono« Wnguritrairbf lknaaor LL LIQUID LIMIT,percent
1c) Rder b tex d IS1M D 1596e1 b a defnlmn d N,n rI«rnyy mrnoltla�cariaia+kss 1aa
Regale Dernty tmrssR balarm Nvahaa c«reea br oerbuoen peswra PI PLASTIC INDEX
ld) lxld'e'r,e]Yea wexp.1/2 urc«Mted c.pp ma9et
■ �1 The DlscuWon In The Text Of This Report Is Necessary For A Ploper Understarding
a The Nature OI The Material Presented In The Attached Logs
Plate
Creative Engineering Options 1NC. LEGEND
Sound Mazda 8
A Fhn P201dry h ee Geascknces
t
1 _
1 oaza 1ed 212M4 Test Pit No, 1 Elevation: 98feat
1 -
1 Symbols Soil Description W(%) _
D Brown,silty fine to coarse SAND,moist,loose,trace rounded gravel,few bricks,occasional
SM boulder(FILL)trace sandstone 12.4
1 StillBlack,silty,fine to medium SAND,mist,medium dense,scattered mots(TOPSOIL)
5
ML Gray,mottled SILT,moist,loose,(flood deposit?)
1 BOH Test Pit terminated at 6.0 feet below exlsdrg grade.
No groundwater encountered during excavation.
1 10
1
15
1
1
1 Logged by: DA Test Pit No. 2 Date: 12/28/94 Elevation: 97.5 feet
Soil Description
0
1 Sod and Topsoil to 6 inches
r1r1r. Brown,fine to coarse SAND,moist,medium dense,some rounded gravel,occasional
r�}fir. SP cobbles,trace silt
11Jyl•
Gray-brawn,fine,sandy SILT,moist,loose,trace construction debris,drain line at 4.5 feet,
1 ML surrounded with wasted rock(Gay t1e)
5 Gray,mottled,sandy SILT,moist,loose
BOH Test Pit laminated at 5.5 feet below existing grade.
No groundwater seepage encountered during excavation.
1
1e
1
1 15
9 alia anc«dgi me depicted m not er,l our riy rep Ian at Ilia line end l es grid lo this exploratory hale,nwdlied o erg'rieer th teals,
aneryva end by others o The/ere not nesimiedio this to r/atiw d drier lines and ucataia We cannel accept responvdily f«lha use«
inlerprelalian q'dliera d inl«malion presede0 an this lop
1 •Test pit elevations approximately determined by eye Wth respect to a temporary benchmark,dre top of the S.E.bolt of
the light standard in the N.E.corner of the property,at an assumed elevation of 100 feet
1 � Plate
�
Creative Engineering Options INC. TEST PIT LOG 9
��..
n Flan RaalTg an vie Sound Mazda Geacicr>as
I
!J
. 1 Logged by: DA Date: 12/2 Test Pit No. 3
8/94 ■ Elevation: 95 feet
Symbols Soll Description W(%)
0 OL Sod and topsal to 12 inches
ML Gray,mottled,sandy SILT,wet,medium dense,trace rounded gravel
BOH Test Pit terminated at 3.0 feet below exlsdlg grade.
No groundwater encountered during excavation.
5
to—
Logged
1
1 15
�J
by. DA Test Pit No 4
17 Date: 1228194 Elevation: 95.Ofeet
Sall Description
0 Glo ray- own,gran a sandstone,mast, se
OL Gray SILT,moist.medium dense,several roots(TOPSOIL)
SMML Brown,mottled,sandy SILT,mast,medium dense,sand in lenses 8.8
Bqi Test Pit terminated at&0 feet below existing grade.
I' No groundwater,seepage encountered during excavation.
5
10
15
Place
Creative Engineering Options e+c. TEST PIT LOG' �w Sound Mazda 10
y A FFn Ra¢I[!ng In Cxmdenas
Ij J
it
Logged by: DA
Date: 12128/94 Test Pit No. 5 Elevation: 96 feet
Symbols Sol[Description W(%) rr
0 OL Sod ,d Topsoil W 6 inches
am Gray,silty,him to rnedium SAND,mist.medium dense,1111114,founded gravel,low cobbles(FILL)
ML Bmwn,sandy SILT,molst,medium dense,scattered roots(FILL)
P1 Black.fibrous PEAT,mixed with coal slug,moist wit(possible fill) 44.1
5 sm Gray to red-brown,silty,fine SAND,moist,medium dense
r.
SP
Red-brown,firs,SAND,wet medium dense
Gray,silty,rim SAND,wet lose,scattered roots-(flood deposit?)
SM
10
BOH Test Pit terminated at 11.0 feet balm existing grade.
Light groundwater encountered at 6 feel during excavation.
15
Logged by: DA
Date: 12/28/94 Test Pit No. 6 Elevation: 96.0 feet
0 Soil Description
GM Black,silly,sandy GRAVEL,miist,loose,(fill)
C.... SM Gray,silty,fine to medium SAND,mist,bow,trace rounded Gravel(fill)
ML Brown,sandy,SILT,moist,loose,scattered roots(possible Topsoil)
Brown."Whied.sandy SILT,moist,loose LL-41 37.5
6 ML P1-13
send lenses
SP Brown,trottied,firs,to medium SAND,moist,towel,bow,scattered wood fragments(fluid
depost)
10—, Bdi pit sides caving below 6 feet
— Test Pit terminated at 100 lest below existing grade.
No groundwater seepage imcc,untered during excavation.
Creative Engineering Options WW, TEST PIT LOG Plate
IF_%.F 9�� I
W�"ir� Sound Mazda
• .eD�-ist u-: .Y+n"r}=S:i4a ..-...�1'<.i: v MsroN x....�' .•..,
o�e: 1ed 2/26/94 Test Pit No. 7 Elevation: 96.5feet
Symbols Soil Description W(%)
Gray,uushed rock surfacing,moist medium dense(FILL)
SP Gray-brown,fine to medium SAND,moist medium dense,(possible Nl)
ML Gray,fine,sandy SILT,mou4 medium dense,trace mad fragemnts(possible fig) 35.0
Gray,fine,sandy,SILT,moist loose
5 ML
itiryl•
r1rLr• Gray,fate to medium SANG,moue to wet Was,trace peat
OP Brown.merge,sandy GRAVEL,wet medium dense
801-1 Teat Pit terminated at 9.0 feel below existing grads.
10 Groundwater encountered at 6 feet during exmadon.
15
Logged by: DA
Date: 1228/94 Test Pit N o■ V Elevation: 96.5 feet
Soil Description
B Topsoil and sod to 6 inches
SP Brown,fine to coarse SAND,moist,medium dense,little rounded gravel,trace silt 11.0
1•ti•
i1i r• SP Brown,fine to medium SAND,moist.loose
ML Gray-brown,SILT,moist loose(Topsoil) 35.0
Brown,mottled,fine sandy SILT,moist.medium dense
5 ML
7
GP Brown,fine to coarse sandy GRAVEL,moist.medium dense
10 BCH Test Pit terminated at 9.5 feet below existing grade.
No groundwater seepage encountered during exravadon.
is—
Creative
^r^ Engineering Options cow. TEST PIT LOG piste
�cv �Frm LrghsKc Sound Mazda 12
�3
1
Date: 12J2 DA Test Pit No 9 Date: 1Z28/94 ■ Elevation: 96.0taet
1 �
Symbols Soil Description W(%)
1 g OL Topsoil and fig to 9 inches
ML Brown,fine,sandy SILT,moist,loose,scattered roots I
1 Gray-brown,mottled,fine,sandy SILT,moist,medium dense,occasional sand lenses 46.7
ML
S LL-at
1 i i1}• Brown,fine to coarse SAND,moist to wet,medium dense,some rounded gravel
SIR PI-15
f'r r• -gravel lenses
♦.L.
ftif`f•
e.e.f.
BOH Test Pit terminated at 8.5 feet below existing grade.
1 t0 Light groundwater encountered at 6.5 feet during excavation.
1
15 I
1
1 �
1
1 II
1 � -
I�
1
�l
1
1
1 �
Creative Engineering Options wc. Plate 1
TEST PIT LOG
1 ` �" nFYm long„sec•em Sound Mazda 13
�l
-kill
�11
APPENDIX B
94-1550
-till, LABORATORY TESTING PROGRAM
r
n
�u
- _ T
' Pa
Geotechnical Engineering Study e 34 g
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
APPENDIX B
' Laboratory Testing Program
94-1550
IL
' General
We conducted a series of selective laboratory tests on carefully selected representative
^
' soil samples. The results were used to help verify or modify the field classification of the
soils encountered and to help evaluate the soil's geotechnical behavior. A brief
description of each of the tests performed for this study is provided below.
' The results of laboratory tests performed on specific samples are provided at the k.
appropriate sample depth on the test pit logs, or on test data sheets attached to this
' Appendix.
Please understand that test results may not accurately represent the overall, in-situ soil
' conditions. Results must be interpreted. Our recommendations are based on our
interpretation of test results, along with other information available to us. Test results help
' guide our engineering judgement. We are not responsible for the interpretation of
these data by others. L
' Soil Classification
All soil samples were visually examined in the field by our engineer at the time they were
' obtained. They were subsequently packaged in moisture-proof containers and returned
to our Redmond office where they were re-examined and the original description was
' verified or modified, as necessary. With the help of the information obtained from
classification tests, the samples were described in general accordance with the qualitative IF
USCS, ASTM Test Method D 2487-83. The resulting descriptions were included at the
' appropriate sample location on the individual test pit logs. The attached Legend, Plate
8, provides a brief summarization of the USCS system.
1 Ir
Geotechnical Engineering Study Page 35
95-1550 Sound Mazda Sales and Service Facility
February 6, 1995
Moisture Content
Moisture content tests were performed on several representative samples obtained from
the exploratory test pits. The purpose of this test is to approximately ascertain the mate-
rials' in-situ moisture content. The moisture content is determined in general accordance
with ASTM Test Method D 2216-80. The information obtained assists us by providing a
qualitative correlation with soil strength and compressibility. The results of these tests are
included at the appropriate sample depth on the test pit logs.
Atterbera Limits
We performed an Atterberg Limits test on two of the samples of finer grained soil in an
effort to better determine the soils plasticity characteristics and as an aid in classification
J� of the soil. This test includes both a liquid and plastic limit, which were performed in
general accordance with ASTM Test Methods D-423-66(72) and D-424-59(71), respec-
tively. The Plastic Index, the difference between the Liquid and plastic limits, is then
determined. The results of the Liquid limit provide a measure of the tested soils' shear
strength and is analogous to the Direct Shear Test. When coupled with the Plastic Index,
the results help us to classify the in-place soil on the basis of these soil characteristics.
The results of this test are presented at the appropriate location on the applicable test pit
log.
-'. Grain Size Distribution
A detailed grain size analysis was conducted on one of the retrieved samples to
determine the overall distribution of the soil's particles. The information gained from these
analyses help to provide a detailed description and classification of the in-place materials.
In turn, this information helps us to understand how the in-place materials will react to
construction activity, groundwater seepage and foundation loading. The results are
presented on Plate 14, Gradation Curves. Classification symbols are also provided as
' part of the appropriate individual sample descriptions on the test pit log.
1
1
ONE I lium
a
.�1
' DISTRIBUTION
94-1550
3 Copies Mr. Scott E. Anderson
Anderson and Boone Architects
525 Columbia Street NW, Suite 201
�., Olympia, Washington 98501
1 Copy Mr. Rich Snyder
Sound Ford
750 Rainier Avenue South
' Renton, Washington 98055
' gm/Soundmaz.Rpt/eb21
' VI. REFERENCES
' 1. Soil Survey of King County Area, Washington. United States Department of
Agriculture, Soil Conservation Service. November 1973.
2. Geotechnical Engineering Study. 95-1550 Sound Mazda sales and Service Facility,
February 1995
' 3. Stormwater Management Manual for the Puget Sound Basin. Washington State
Department of Ecology. February, 1992.
' 4. Waterworks. Software for Hydrology. Version 2.7. Engenious Systems, Inc.
Seattle, Washington.
t5. Preliminary Drainage Report for Renton Dodge Dealership. ESM, Inc. Federal
Way, WA. April 1994
6. Flowmaster. Version 4.1. Haestad Methods, Inc. Waterbury, Connecticut.
1
1
' 10